Talk:MVS

Non-POV claims
> Japanese mainframe manufacturers Fujitsu and Hitachi both repeatedly and illegally obtained IBM's MVS source code and internal documentation in one of the 20th century's most famous cases of industrial espionage.[citation needed]

I found some references to this from old ComputerWeek articles from 1980s, but even those don't read quite like the above, sounds like a much more complex case.... the above sounds like something out of IBM lawyers. — Preceding unsigned comment added by 2601:18F:600:E20:99A6:13B5:83E8:B008 (talk) 01:45, 4 September 2016 (UTC)


 * Here's a U.S. Congressional hour of hearings testimony, including FBI, fines, etc.: http://www.fas.org/irp/congress/1989_cr/h890712-japan.htm — Preceding unsigned comment added by 72.251.58.10 (talk) 18:06, 18 January 2017 (UTC)

Post-MVS features
Should features mentioned on this page be moved to the OS/390 page if they first appeared in OS/390 or to the z/OS page if they first appeared in z/OS? Guy Harris 02:13, 3 February 2006 (UTC)


 * Presumably this would be covered by the reorganization discussed below. Guy Harris 18:27, 19 October 2007 (UTC)


 * First and foremost, keep in mind that OS/VS Rel.2 (a.k.a. VS2 or MVS), MVS (MVS Rel.3), MVS/SP, MVS/XA, OS/390 and the early z/OS are nothing but enhanced, expanded releases of the original OS/360 PCP stock. The name changes are confusing though they were necessary for marketing and legal reasons. While the early OS/360 versions (MFT an MVT) were "bundeled", all subsequent releases were leased / licensed software. As the operating systems evolved, so did the terms and conditions of the licenses. Case in point well worth noting: If it was written respecting the rules, any program which once worked and ran under OS/360 MFT/MVT could have and often did run on all subsequent operating system releases and will still run on the latest z/OS release. AndreasCA (talk) 17:37, 26 October 2008 (UTC)

MVS is still the name of today's z/OS products' core services. Therefore, it would be better to structure along the lines of major enhancements (see: "z/OS V1R10.0 MVS ...").


 * I think AndreasCA's comment "OS/VS Rel.2 (a.k.a. MVS) ... and the early z/OS are nothing but enhanced, expanded releases of the original OS/360 PCP stock" is an exaggeration. I was an IBM employee when MVS was introduced and was told by some of IBM's best technical people that MVS was a complete re-write in a different language (PL/S instead of Assembler). It's true that "If it was written respecting the rules, any program which once worked and ran under OS/360 MFT/MVT could have and often did run on all subsequent operating system releases and will still run on the latest z/OS release," because IBM took backwards compatibility very seriously, if only to avoid having to write all its software products simultaneously. However MVS had completely different memory management and security from SVS, which was just MVT with virtual memory bolted on. Functional structure of IBM virtual storage operating systems Part II: OS/VS2-2 concepts and philosophies by A. L. Scherr makes these and other differences clear. In short, these systems retained very similar externals but had very different internals. -- Philcha (talk) 18:28, 26 October 2008 (UTC)


 * Philcha understood correctly that IBM partially (re-)wrote / replaced substantial parts of the old OS/360 code by new functions written mostly in PL/S, namely those parts which had to be changed to go from vertical mapping of regions to the horizontal one. Also, a lot of new functions and features were added (VSAM, VTAM) which replaced similar ones from the OS/360 era, eg. BTAM/QTAM, QISAM and many releases later TCAM, CVOL catalog management and others. The "completely different memory management" talk refers to is a fine example of a lot of IBM Marketing hype. The old MVT memory management was partially eliminated. The rest was ported to MVS with little more than "minor" changes as the new MVS memory management of virtual storage, the same 'ol GETMAIN, FREEMAIN, subpools, FQEs (though better protected). Of course, a completely new real-storage management was added, including a completely redesigned swapping and paging. The next big partial rewrite occured when IBM reworked MVS/SP to support 31-bit addressing. At no point in the evolution did IBM rewrite OS/360 MFT/MVT. Although many original components are still around I can't imagine anyone except IEFBR14 still being in its original state. AndreasCA (talk) 19:33, 26 October 2008 (UTC)


 * Also, :Philcha wrote "MVS had completely different memory management and security from SVS, which was just MVT with virtual memory bolted on." may be misleading since SVS was really an MFT extension with 16 vertically mapped partitions, mapped in virtual storage, but included JES1 or JES2, TSO, VSAM and VTAM. Though the last two I could be wrong because I used TCAM for TSO and had no ISAM on that 370/158 VS1 system (1974-1975). No new or better security features were introduced with either VS1 or VS2. RACF wasn't available or usable until MVS Rel.2.3 (or thereabouts, say 1979). MVS Rel.2 used the exact same security components (Assembler programs, SYS1.UADS, etc.) as MFT and/or MVT did, all Assembler modules, all ported from MFT and/or MVT. AndreasCA (talk) 20:41, 26 October 2008 (UTC)


 * "GETMAIN, FREEMAIN, subpools, FQEs" remained the same for backwards compatibility, and because they seemed to do what was needed at the time. However internally MVS' memory managemnt was totally different, because it was more efficient (no more fragmentation) and inherently more secure - in 1976 IBM announced that it would treat corruption of one MVS address space by another without the help of a rogue SVC as a priority 1 bug, something they had not felt confident of doing with MVS' predecessors. -- Philcha (talk) 21:33, 26 October 2008 (UTC). Unfortunately Philcha quotes from IBM Marketing literature and is getting confused, Security and RAS, though related, are two different topics. MVS Rel.2 fragmented virtual storage no more and no less than MVT fragmented real storage. However MVS generally makes better use of real storage than MVT does. AndreasCA (talk) 17:45, 27 October 2008 (UTC)

From OS/360 PCP to z/OS, MVS has been continually expanded, enhanced and adapted. And it shows. There are many "questionable" features and quirks that have their justification and origin in a long forgotten world of System/360 with its SIO and CCWs and the OS/360 designed to hog not much more than the 56KiB of real core storage. AndreasCA (talk) 20:41, 26 October 2008 (UTC). Coming back to "questionable" features and quirks, here are some of them:
 * many files have 80-byte long records and the last 8 or 9 are reserved
 * MVS assists but it is still the users (plus add-on software) who manage disk space (ref: x37 abends).
 * the dataset catalog isn't a directory but there is exactly one directory called VTOC per disk
 * DOS/360 and OS/360 and their offspring, all use CKD disk formats
 * AndreasCA (talk) 17:45, 27 October 2008 (UTC)

31-bit addressing
OS/360 right up to MVS/SP only supported 24-bit addressing. As the underlying hardware progressed it supported 31-bit (XA and ESA) and now (as z/OS) 64-bit addressing were added.

Should this say "it supported 32-bit (XA and ESA)"? No, because the 32nd bit, the top/left-most bit is used to distinguish between 31-bit and 24-bit addressing modes, as well as being used as a special "end-of-list" marker known as the VL-bit. Both adressing modes can be intermixed in the same program, as documented in the respective "Princple of Operations" manual. Special instructions were introduced to let any program switch from one addressing mode to another AndreasCA (talk) 18:31, 26 October 2008 (UTC)
 * There was an early attempt at 32-bit addressing in the System/360 Model 67, and the weird bugs deriving from unsigned addresses in a milieu where sign bits hadn't previously participated were legendary horror. When Extended Addressing (XA) came it did in 31-bit form to avoid repeating those problems.  When System/390 extended the addressing to 64 bits, a lot of us said "surely you mean 63 bits - no sign, right?".  The response from IBM was that they had spent so much time and effort dealing with public relations etc. fallout from the 31-vs.-32 bit decision that there was only one acceptable answer to the 63-vs.-64 bit question. RossPatterson 03:48, 12 April 2006 (UTC)
 * Interesting. How did 64-bit systems handle variable-length argument lists in subroutine calls (see below re CALL macro)?Philcha 05:37, 19 October 2007 (UTC)

The high order bit running in XA mode (31-bit addressing) was typically used to indicate the last element in a series of link listed addresses, i.e. there were not any more tokens in the chain.
 * That's right. More specifically, from DOS/360 and OS/360 onwards subroutine calls passed the addresses of their arguments (like references in C); the last of a variable-length set of arguments had the high bit set to 1 (by the CALL macro in Assembler; by compilers for high-level languages). Philcha 05:37, 19 October 2007 (UTC) In all cases of 24-bit adressing modes the hardware always did and still does ignore all 8 high-order bits. Only the lower 24 bits of an address are used to access memory.AndreasCA (talk) 18:31, 26 October 2008 (UTC)

I dont' see any reference to MFT an ancestor of MVT.--Les 14:25, 12 December 2006 (UTC) Correct, though technically a revised PCP was released as MFT. Going back to 1968 I never knew of anyone having ever used OS/360 PCP. MVT was as much a revised MFT as MFT was a down-scaled "lighter" MVT. To use MVT one needed at least a 512KiB machine (typically 360/65s) whereas most MFT shops had 360/40's or 360/50's with 256KiB. AndreasCA (talk) 18:31, 26 October 2008 (UTC)

Benefit of running MVS now z/OS
MVS will run the processor at 100% utilization while still performing real work. Try that on UNIX or Windows based systems.
 * More precisely, MVS requires hardly any tuning to run the processor at 100% utilization while still performing real work. In the early 1970s the large UK clearing banks ran their overnight systems at 100% just to get all the work done, but that required careful system design and heavy tuning of MVT. Philcha 06:19, 19 October 2007 (UTC)

Need to restructure IBM operating system articles?
Long discussion on the topic, with a plan of new structure, has been moved to Talk:History of IBM mainframe operating systems. Please continue there.

--Kubanczyk 12:46, 24 October 2007 (UTC)

Rewrite of Job Control Language in progress
As part of the proposed restructure of articles on IBM mainframe operating systems (above), I've rewritten Job Control Language to: cover IBM's DOS/360 and its descendants as well as OS/360 and its descendants; focus more on the facilities and flavour of the 2 JCLs rather than on details of some statement types and some of their options. Please comment in Talk: Job Control Language. I'd be particulary grateful for more info on DOS/360 and its descendants, especially after 1980 - I only used DOS JCL a handful of times, and only in the late 1970s.

The rewrite does not currently take account of Truthanado's point in Talk: Job Control Language about use of "JCL" by computer suppliers other than IBM, which may entail further restructuring of articles about JCLs.Philcha 23:47, 20 October 2007 (UTC)

Name standardization
Some time ago there was a push to standardize the names of articles related to exclusive IBM products (OS/2 → IBM OS/2). I've moved a few of the more obvious ones... would the move here be appropriate? /Blaxthos 17:04, 28 October 2007 (UTC)
 * How this ummmm "standardization" effort relates to official Wikipedia guideline WP:COMMONNAME? The two seems to be in conflict, aren't they? May I ask about the reasons for this renaming push? --Kubanczyk 17:38, 28 October 2007 (UTC)
 * Please do not rename until merger proposal decided (see below). If the pages are merged, renaming will be unnecessary. Philcha (talk) 21:10, 25 November 2007 (UTC)

Merger proposal
To reduce duplication of content re features inherited from MVS's predecessors and to fit into the framework provided by History of IBM mainframe operating systems. —Preceding unsigned comment added by Philcha (talk • contribs) 21:07, 25 November 2007 (UTC)

Modern definition of MVS?
I'm a person who sometimes uses z/OS but I did not cut my teeth on IBM mainframes. I encounter the term MVS often, so I came here hoping to see a definition, but I don't see what I'm looking for. I'm not looking for "Multiple Virtual Storage" which may be the term's origin but clearly has little relevance to it's current meaning. And I'm not looking for "MVS was the most commonly used operating system on the System/370 and System/390 IBM mainframe computers," (note the past tense), or "MVS is no longer supported by IBM." This may be one meaning of the term, but it is not the way the term is currently used (in my experience). IBM still uses the term widely, see http://www.ibm.com/systems/z/os/zos/bkserv/r9pdf/#mvs, and IBM's usage doesn't fit the definitions presented in this article. If MVS is just an old name for z/OS, then why does IBM still use the term so often, in current publications?

I'm afraid this sounds like a rant. I don't mean it to be, I'm just suggesting that this article should start with the information that most non-mainframe people are going to be looking for -- a straightforward definition of the current meaning of the term. Historical information can come after that. I would suggest a definition to you, if only I knew what it would be. MVS currently seems to be used as a generic term for the non-POSIX portion of z/OS, as far as I can tell, but as a non-expert on the subject I'm not really sure (which is why I turned to Wikipedia). I have not been able to find the answer on the IBM website either. Doctorpepper (talk) 19:27, 19 April 2008 (UTC)


 * Interesting question. I just googled for "MVS" and found (among a load of irrelevant stuff, nothing to do with IBM OSs):
 * FolDoc on OS/390 - appears to suggest that OS-390 = MVS + Unix. If true, that would support your "MVS currently seems to be used as a generic term for the non-POSIX portion of z/OS".
 * a UK contracts site that is try into recruit for "MVS" contracts - so the term is still in use and widely recognised, despite the fact thatIBM introduced the OS/390 "brand" in 1995.
 * I'll ask around. Philcha (talk) 20:11, 19 April 2008 (UTC)


 * I'm afraid that in this field history is important, so if readers don't want to read about the history, they may have serious problems with figuring out anything. In the same way, to provide an example from the PC field, most people say "DOS commands" instead of "Windows Command Prompt commands" (whatever...). Just try to explain this to somebody that does not want to know a bit of DOS/Windows history. --Kubanczyk (talk) 21:16, 19 April 2008 (UTC)


 * I *think* that in a modern context, MVS refers to the supervisor portion of z/OS. I'd say that MVS is to z/OS what linux is to gnu/linux. Ivan Scott Warren (talk) 11:45, 16 March 2009 (UTC)

While much new code was written in BSL and  PL/S, MVS inherited a huge amount of Assembler code from  OS/360. Shmuel (Seymour J.) Metz (talk) 22:54, 4 June 2010 (UTC)


 * For those of us who worked on MVS, the acronym became a metonym. Metonymy is a figure of speech in which a thing or concept is not called by its own name, but by the name of something intimately associated with that thing or concept. For instance, "Hollywood" is used as a metonym (an instance of metonymy) for American cinema, because of the fame and cultural identity of Hollywood, a district of Los Angeles, California as the historical center of movie studios and movie stars. Another example is "Westminster," which is used as a metonym for the Parliament of the United Kingdom, because it is located there.


 * In the early part of my career (beginning in 1967) I was a DOS/MVT/MVS systems programmer. When I got out of day to day SP work and became a manager, MVS was etched in my mind as THE operating system. As MVS evolved into z/OS the name just stuck for me and all my fellow old-timers. So forget your quest to figure out the current definition, ain't gonna happen...67.183.176.27 (talk) 22:58, 14 November 2011 (UTC)Bill Anderson 


 * Well, z/OS V1R11.0 Information Roadmap z/OS V1R10.0-V1R11.0 speaks of "documents for MVS™ (Base Control Program)", and of "MVS and other z/OS elements", suggesting that what IBM calls "MVS" these days is a component of z/OS. Networking on z/OS speaks of "MVS application[s]" and "z/OS UNIX application[s]", suggesting that "MVS" might be the component of z/OS that supports the "classic" part of z/OS rather than the "support UNIX APIs" part, i.e. the component that isn't descended from the stuff added in MVS/ESA OpenEdition, or, to put it another way, not the "Unix System Services" part. Guy Harris (talk) 01:32, 15 November 2011 (UTC)

History and names
First, the genealogy of z/OS is a bit longer than the article states. There were also several add-on program products that were eventully meged into the base. Off the top of my head:


 * OS/VS2 Release 2 through 3.8


 * MVS/System Extensions
 * Release 1 based on 3.7 and SU7
 * Release 2 (SE2) based on 3.8 and SU64
 * MVS/SP Version 1
 * MVS/SP Version 2 (MVS/eXtended Architecture)
 * MVS/SP Version 3 (MVS/ESA)
 * MVS/SP Version 4 (MVS/ESA)
 * Release 3 introduced OPEN EDITION (Unix)
 * MVS/ESA Version 5
 * OS/390 Version 1
 * OS/390 Version 2
 * z/OS

Unix came in with MVS/SP 4.3, under the name MVS OPEN EDITION.

Several older add-on packages were swallowed up by TSO/E and DFP; the latter was eventually renamed to DFSMS and incorporated several other add-on products.

Officially Unix System Services does not have an acronym; USS refers to Unformatted System Services, a part of VTAM, and by extension to equivalent services in the TN3270 server. Shmuel (Seymour J.) Metz Username:Chatul (talk) 14:11, 7 July 2010 (UTC)


 * I've edited the article to address some of the above. In the process I noticed a claim that MVS was the most common mainframe operating system. I've always understood the DOS/VSE, VSE/AF, VSE/SP. VSE/ESA and z/VSE were each, in their day, more popular. If anybody has any documentation one way or the other, please add a citation. Shmuel (Seymour J.) Metz Username:Chatul (talk) 15:44, 8 July 2010 (UTC)


 * Where does MVS fit into this? I've just merged the article in and I can't find many references to it.--Salix (talk): 12:52, 28 November 2010 (UTC)


 * As mentioned in Talk:MVS/370, IBM introduced the term MVS/370 to refer to all versions of MVS that required S/370 (24-bit address) architecture rather than XA (31-bit addressing) architecture . Shmuel (Seymour J.) Metz Username:Chatul (talk) 12:25, 29 November 2010 (UTC)

Merge MVS articles
I proposed MSV, MVS/370, MVS/XA, MVS/ESA be merged into this article.--Salix (talk): 05:00, 2 October 2010 (UTC)


 * MSV?


 * approve, however
 * Should the gaps be filled in first?
 * Is there an editor willing to undertake the work? I can help, but I doubt that I'd have time to do it all myself. Shmuel (Seymour J.) Metz Username:Chatul (talk) 01:01, 3 October 2010 (UTC)


 * I've now merged the articles is. There are probably quite a few repeated part and gaps still remain.--Salix (talk): 12:49, 28 November 2010 (UTC)

DSS was not a hypervisor
DSS was not qa hypervisor, it was an interactive debugging facility for the operating system. It was much more primitive than the similar TSSS in TSS/360.

Also, IBM killed DSS twice. After the announcement that Selectable Unit 7 would remove support for DSS, the user organization Share passed an Imperative requirement to reinstate DSS, and IBM caved in. Rumor had it thaqt the massive code change required to allow DSS to coexist with SU 7 was actually a single line. Shmuel (Seymour J.) Metz Username:Chatul (talk) 17:46, 20 July 2011 (UTC)

References to MVS/370
There are several problems with the references to MVS/370 in this article


 * MVS/370 refers to all of OS/VS2 (MVS), MVS/SE and MVS/SP Version 1


 * MVS/370 has not been supported for decades, so the reference to being supported should be removed.


 * The earliest MVS/370 was OS/VS2 R2; the latest was MVS/SP V1.3 (1.3.7?)

Shmuel (Seymour J.) Metz Username:Chatul (talk) 21:22, 16 August 2011 (UTC)

Reverted of good faith edits by Rfc1394
My edit summary for my revert of two edits by Rfc1394 was truncated. In its entirety: "The comparison of PDSs to ZIP files is marginal, ZIP files are not really meant to be updated, whereas PDSs are, and the above/below the line distinction is an RMODE distinction whereas the description describes AMODE differences.". And to further expand on the AMODE/RMODE thing, the residence mode (RMODE) of an application controls whether it runs below (RMODE(24)) or (potentially) above the line (RMODE(ANY)), whereas the addressing mode defines if the program uses 24 bit (AMODE(24)), 31 bit (AMODE(31)), or in either (AMODE(ANY)), based on the caller. While a program running AMODE(24) must be RMODE(24), programs running with 31 bit addressing may (and commonly do) run below the line, so that the can be easily called from 24 bit programs. There are additional complications (newer versions of the OS support 64 bit addressing and programs that have bits loaded into separate areas), but they're not really relevant here. Rwessel (talk) 05:43, 4 August 2014 (UTC)


 * In addition, AMODE and RMODE are attributes of individual load modules or program objects, not of entire applications. Further, an RMODE(24) AMODE(24) module can still allocate storage above the line, using the appropriate parameters of the GETMAIN or STORAGE macro, and an AMDE(31) RMODE(ANY) module can still allocate storage below the line. Shmuel (Seymour J.) Metz Username:Chatul (talk) 20:42, 4 August 2014 (UTC)

Clarification of extension versus extensions
The MVS/SE program products were Extensions (plural); however, the processor feature 3033 Extension Feature is singular. Shmuel (Seymour J.) Metz Username:Chatul (talk) 17:31, 24 January 2017 (UTC)

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 * The first edition is indeed gone from bitsavers, but I notice that the second edition is still there at . Shmuel (Seymour J.) Metz Username:Chatul (talk) 20:10, 11 January 2018 (UTC)


 * Actually, the first edition is still at bitsavers, but that's a different scan, and doesn't seem to be as good a scan as the archived version. Guy Harris (talk) 20:35, 11 January 2018 (UTC)

image
The lede image showing the Hercules console really seems to hsve nothing to do with MVS. Does some Herculean have a screenshot of an actual MVS console display that could be used instead? Peter Flass (talk) 13:44, 20 June 2019 (UTC)

ipad problem
This page seems to go crazy with Safari/iPad - keeps flashing, possibly reloading. This is the only page I’ve seen that this happens to. Peter Flass (talk) 02:52, 28 January 2020 (UTC) Plus one to that. — Preceding unsigned comment added by 104.185.77.31 (talk) 03:06, 12 October 2020 (UTC)

How does evolution differ from history?
The article has sections called MVS and MVS. Either the sections should be merged or the names changed to make it clear who did what to whom. Shmuel (Seymour J.) Metz Username:Chatul (talk) 03:24, 19 July 2020 (UTC)

Confusing text in MVS
I find the paragraph Modern versions of MVS (e.g., z/OS) also support POSIX-compatible "slash" filesystems along with facilities for integrating the two filesystems. That is, the OS can make an MVS dataset appear as a file to a POSIX program or subsystem. These newer filesystems include Hierarchical File System (HFS) (not to be confused with Apple's Hierarchical File System) and zFS (not to be confused with Sun's ZFS). in MVS to be confusing. I'm not aware of anything called a slash filesystem, and the second sentence is not true. To clarify:


 * MVS-OE uses MVS datasets as containers for Unix filesystems.
 * A user can specify a path (Unix file) on a DD statement or dynamic allocation.
 * In some, but not all, cases, a classic MVS program can use a Unix file.
 * IBM has enhance some Unix utilities to support special systax for referring to classic MVS datasets.
 * Unix programs that do not use the enhanced library and that have not been modified are not able to use classic MVS datasets

Before I edit that text I want to understand what the author is trying to say. Shmuel (Seymour J.) Metz Username:Chatul (talk) 04:19, 19 July 2020 (UTC)

New section Upgrades to MVS
I've created an Upgrades to MVS section that lists enhancements that came as optional features or products rather than as new releases or sub-releases. I currently don't show any of the ICRs prior to OS/VS2 Release 3.7. If anybody spots any errors or omissions, or has relevant announcements that they can link to, please edit appropriately. I plan to create subsections for the more important products, probably including DFP, DFSMS, MVS/SP and TSO/E. I will probably describe the products that each replaces as leadins, rather than giving them their own subsections.

Would the list of Incremental change releases, Field Developed Programs and Program products be better as a collapsible table? Shmuel (Seymour J.) Metz Username:Chatul (talk) 22:31, 2 August 2020 (UTC)

Contents, location and organization of timeline?
Now that IBM has put up a repository of announcement letters at https://www-01.ibm.com/common/ssi/ going back to 1981, I'm considering building a timeline for selected MVS software, starting with User:Chatul/References as a sandbox. I'm currently thinking of


 * Products in the DF/foo, DFP and DFSMS line
 * Products in the MVS/SE and MVS/SP line, through z/OS
 * Products in the SCRIPT line
 * Products in the SPF line
 * TSO/E
 * MVS/XA replacements for free access methods, e.g., BTAM/SP, GAM/SP
 * Communications products, e.g., ACF/VTAM

I'd like feedback on Thoughts? Shmuel (Seymour J.) Metz Username:Chatul (talk) 17:59, 1 June 2021 (UTC)
 * What products to include or exclude
 * Whether to put the timeline in the MVS article or elsewhere
 * Whether to put everything in a single table or create multiple tables, either by category or chronology
 * Whether to make the table(s) collapsible or sortable?

Copy information from Draft:Data Facility Storage Management Subsystem (MVS)?
I've created the article Draft:Data Facility Storage Management Subsystem (MVS), with citations to all of the relevant IBM announcement letters that I could find. Some of the information should fit in well here, although I suggest keeping DFP and DFSMS text short, with a main template once the draft is in the article namespace. --Shmuel (Seymour J.) Metz Username:Chatul (talk) 13:23, 23 June 2021 (UTC)

Multitasking with a Variable number of Tasks
The article currently says OS/360 MVT (Multitasking with a Variable number of Tasks) but the article in that link says Multiprogramming with a Variable number of Tasks (MVT). The name Multitasking with a Variable number of Tasks is redundant. My memory is fuzzy but I do not remember the name being redundant like that. I cannot find something authoritive but one of those two names is incorrect. Sam Tomato (talk) 06:10, 6 October 2022 (UTC)
 * I'm not entirely sure I see the redundancy (an OS could support multitasking with a fixed maximum of N tasks, or it could support multitasking without a fixed maximum, with any maximum being imposed based on available system resources such as main memory), but, indeed, at least according to the OS/360 Concepts and Facilities manual, Seventh Edition, it's "multiprogramming with a fixed number of tasks (MFT)" and "multiprogramming with a variable number of tasks (MVT)".
 * (Confusingly, MFT with subtasking supports more than one task per partition, so the total number of tasks might not have a fixed limit; only the number of main tasks, or whatever it is that's limited to one-per-partitionk has a fixed limit.) Guy Harris (talk) 06:52, 6 October 2022 (UTC)
 * I've changed the expansions of both MFT and MVT to say "Multiprogramming" rather than "Multitasking", and provided the Concepts and Facilities manual as a reference. Guy Harris (talk) 07:02, 6 October 2022 (UTC)
 * Multiprogramming is correct for both MFT and MVT. The original OS/360 Option 2 (MSS) and MFT only allowed a single task per partition and when IBM added MFT multitasking support it was an option on the SUPRVSOR sysgen macro. --Shmuel (Seymour J.) Metz Username:Chatul (talk) 13:18, 6 October 2022 (UTC)
 * Multiprogramming is correct for both MFT and MVT. The original OS/360 Option 2 (MSS) and MFT only allowed a single task per partition and when IBM added MFT multitasking support it was an option on the SUPRVSOR sysgen macro. --Shmuel (Seymour J.) Metz Username:Chatul (talk) 13:18, 6 October 2022 (UTC)

MVS is the most commonly used OS on IBM Z?
As a result of the present-tensification of the article (most of which is fine), the article now says

"Multiple Virtual Storage, more commonly called MVS, is the most commonly used operating system on the System/370, System/390 and IBM Z IBM mainframe computers."

Does this mean that OS/390 and z/OS are considered to be versions of MVS for the aske of that statement, or are IBM Z systems (and maybe even System/390 systems) mostly still running pre-z/OS (and maybe even pre-OS/390) versions of the OS? seems to be saying the first of those (although I had to fix it not to suggest that the strings "OS/390" and "z/OS" have the string "MVS" as a substring). Guy Harris (talk) 11:16, 27 February 2023 (UTC)
 * MVS remains as a documented component of OS/390 and z/OS. Possibly something like
 * "Multiple Virtual Storage, more commonly called MVS, is the most commonly used operating system on the System/370, System/390 and IBM Z IBM mainframe computers, although it can no longer be ordered as a separate product."
 * There is, however, the question of whether z/Linux has overtaken MVS. Does anybody have relevant data? --Shmuel (Seymour J.) Metz Username:Chatul (talk) 17:18, 27 February 2023 (UTC)

recent edit
A recent edit changed HTML tags to XHTML   tags, changed https://www.ibm.com/common/ssi/ShowDoc.wss?docURL=/common/ssi/rep_ca/2/897/ENUS283-042 to https://www.ibm.com/common/ssi/ShowDoc.wss?docURL=/common/ssi/rep_ca/2/897/ENUS283-042/index.html&request_locale=en, changed Announcement Letters to Announcement Letters and changed IBM to IBM.

The change to url is legitimate. However:


 * 1) There have been recent discussions on changing HTML5 markup to XHTML markup, and the consensus seems to be to leave  alone.
 * 2) Announcement Letters is inappropriate because there is no such department. The body of announcement letters is just one work of many published by the same department. This should remain as changed Announcement Letters.
 * 3)  IBM is inappropriate; IBM has many web sites. This should remain as IBM or be linked as [IBM].

Changing cite document to cite web is more ambiguous; at one time IBM published announcement letters on paper, but I don't know whether they still do. -- Shmuel (Seymour J.) Metz Username:Chatul (talk) 16:02, 2 June 2023 (UTC)
 * Yep. I did all of those things and more; you left out that I deleted dead ...
 * As you know, is a (usually inappropriate) redirect to .  Because of that, a real cs1  is in the process of being created.  The new template will only support a limited subset of the complete cs1|2 parameter set because cs1 has templates that will satisfy most needs.  The new  is intended to support short, published stand-alone sources that are not part of a book, periodical, encyclopedia, website, etc.  If I had not touched your  templates, this would have been the result on the day that the new template goes live:
 * It is interesting to me that you have used for other 'Announcement Letters' in this article... See §MVS/ESA
 * You complain about Announcement Letters. That parameter is an ancient alias of title-note which seems to have disappeared.  I'll look into why it's gone and see if it oughtn't to be restored.  The other alternative for 'Announcement Letters' was type but, that parameter renders in parentheses at a different location.  Cf:
 * As you know, work is an alias of journal (because is a redirect to ) so what you have told cs1 is that you are citing a journal called Announcement Letters.  There is no such journal.  Switching to  means that you are telling cs1 that you are citing a website called Announcement Letters.  There is no such website.  There is, however. a website called IBM → https://www.ibm.com and that is where these letters reside.  As such it is wholly appropriate to use  and IBM.
 * There may have been discussion about v .  I haven't seen it.  But, so long as MediaWiki allows, nay, uses, so will I.  You can see that MediaWiki does use  if you open this version of the article (the version just before my edit – there are no  tags) and then right click → View page source; Ctrl+F  .  The real reason that I switch these tags is because I and other editors use the older syntax highlighter which, admittedly, has its limitations, one of which is that it doesn't understand self closing tags; the edit window gets painted pink.  No one is harmed, and it makes life a bit easier for those editors and me.  If the highlighter gets fixed (don't hold your breath, I'm not) or support for it is withdrawn, then I will have no need to switch  to.
 * —Trappist the monk (talk) 18:04, 2 June 2023 (UTC)
 * The documentation for type says "Additional information about the media type of the source; "; "Announcement Letters" is not a media type.
 * The documentation of website reads "work (required by cite journal and cite magazine): Name of the work containing the source"; "IBM does not satisfy that definition and belongs on publisher. Also, as I noted, some of the announcement letters were printed on paper. In fact, many of those I cited predate the WWW entirely.
 * I believe that it may be time to ask for a 3rd party opinion.
 * I have mixed feelings about ; I used to use it myself until I saw threads deprecating it, but it's not my monkey and not my circus. -- Shmuel (Seymour J.) Metz Username:Chatul (talk) 12:24, 6 June 2023 (UTC)
 * I did not use type (see your OP) so why are you complaining about that?
 * Indeed, IBM is the publisher of an eponymously named website: IBM.com (the publisher's work). IBM is the [name] of the work containing the source where the source is an announcement letter.
 * some of the announcement letters were printed on paper. No doubt.   But, you appear to be citing electronic versions of those announcement letters else you would not have included url.  If you only consulted the paper versions of these documents, those are what you should be citing, not the electronic versions.  And, if that is the case, the upcoming  should be sufficient for you:
 * In the above Document is the default. It can be overridden with Announcement Letter or suppressed entirely with none.   will not support url; that's what  is for. Or, you could link all or part of id with the url.
 * —Trappist the monk (talk) 13:59, 6 June 2023 (UTC)
 * Sorry, it was Guy Harris who inappropriatel changed department (originally work to type.
 * http://ibm.com is, indeed, a web site maintained by IBM, but it is one of thousands that have nothing to do with announcement letters. Nor, as I previously noted, does the documentation of website/work restrict it to domains, and, in fact, it or an alias is required in, e.g., cite journal, even if there is no relevant web site. in the case of, the parameter www.ibm.com/common/ssi/ShowDoc.wss might have been appropriate, but certainly not ibm.com, and [IBM] should have been retained.
 * I originally read the electronic versions, but in the knowledge that they had originally printed on paper, hence my indecision on which template to use. If cite document will no longer support url then I would stick to, in the absence of a more appropriate template supporting url, rather than wikilinking the title or id. -- Shmuel (Seymour J.) Metz Username:Chatul (talk) 11:18, 9 June 2023 (UTC)
 * The full description of the type parameter is:
 * "Provides additional information about the media type of the source. May alternatively be used to identify the type of manuscript linked to in the title, if this is not the final version of a manuscript (e.g. if a preprint of a manuscript is freely available, but the version of record is behind a paywall). Format in sentence case. Displays in parentheses following the title. The reserved keyword  can be used to disable the display of a type.  Alias: medium."
 * This 1) does not indicate what "media type" means and 2) does not clearly indicate to me that "Announcement letter" is no an appropriate value. It gives "Press release" as an example of a valid value; what would the difference between "Press release" and "Announcement letter" be here? Guy Harris (talk) 17:06, 9 June 2023 (UTC)
 * http://ibm.com is, indeed, a web site maintained by IBM, but it is one of thousands that have nothing to do with announcement letters. and earlier you wrote: IBM is inappropriate; IBM has many web sites. You seem to suggest that there are many, possibly thousands of, IBM websites.  That may be true, I don't know, but inarguably, there is only  http://ibm.com and that  is the website you linked that holds the various announcement letter documents which calls into question the validity of the claim http://ibm.com is ... one ... that [has] nothing to do with announcement letters.
 * Nor ... does the documentation of website/work restrict it to domains Umm, what?  The documentation for website at  (link) reads:
 * website: Title of website (when the website has a clear name, use that rather than the domain name); may be wikilinked. Displays in italics. Aliases: work
 * I read that to mean that use of the website's domain name in website is discouraged. supports that.  Use of the domain name in website is correct only when the source is commonly known by its domain name.  You suggested that www.ibm.com/common/ssi/ShowDoc.wss might have been appropriate.  Per the documentation, it is not.  The only value that should be assigned to website is.
 * It occurs to me that if you can convince yourself that the announcement letters are, in a sense, a form of periodical (nothing says that a periodical must be issued on a schedule) then you might write:
 * —Trappist the monk (talk) 17:38, 9 June 2023 (UTC)
 * nothing says that a periodical must be issued on a schedule Perhaps not on a strict schedule, but, for what it's worth, the entry for "periodical" in the Cambridge Dictionary says
 * "a magazine or newspaper, especially on a serious subject, that is published regularly"
 * and the entry for "periodical" in the Merriam-Webster dictionary says:
 * periodical 1 of 2 adjective
 * 1 : PERIODIC TABLE sense 1
 * 2 a: published with a fixed interval between the issues or numbers
 * b: published in, characteristic of, or connected with a periodical
 * periodical 2 of 2 noun
 * : a periodical publication
 * I'm not sure what "regularly" means, but if they're only published when there's something to announce, there could be times when several Announcement Letters are sent out and other times where nothing is heard from IBM in a while. Guy Harris (talk) 18:01, 9 June 2023 (UTC)
 * Did you not notice that I wrote that with a caveat: if you can convince yourself that the announcement letters are, in a sense, a form of periodical...? My experience with periodicals here at en.wiki, is that the periodical publishers do (usually) follow a schedule, but not always.  If you don't like  as a solution, don't use it.
 * —Trappist the monk (talk) 18:11, 9 June 2023 (UTC)
 * And I added some dictionary definitions to indicate that convincing oneself that the annoucnement letters are, in a sense, a form of periodical may be a mistake. What periodicals are published every time somebody has something to announce, and not published if they don't have something to announce?  What are some examples of "not always" that you have experienced? Guy Harris (talk) 19:15, 9 June 2023 (UTC)
 * Yes, I know why you added the definitions. Makes perfect sense to me to be silent when there is nothing to be said... To answer your not always question: usually its a case of combining multiple 'numbers' into a single issue.  Here are some search results looking for articles with multiple-numbers-in-a-single-issue (cirrus search so your results may be different):
 * – ~22,000 articles (timed out)
 * – ~5,300 articles (timed out)
 * – <100 articles
 * Not really uncommon. But, as I said before: If you don't like as a solution, don't use it.  I'm not arguing for or against the  solution; I'm happy with the  solution I demonstrated above.
 * —Trappist the monk (talk) 20:11, 9 June 2023 (UTC)
 * "a magazine or newspaper, especially on a serious subject, that is published regularly"
 * and the entry for "periodical" in the Merriam-Webster dictionary says:
 * periodical 1 of 2 adjective
 * 1 : PERIODIC TABLE sense 1
 * 2 a: published with a fixed interval between the issues or numbers
 * b: published in, characteristic of, or connected with a periodical
 * periodical 2 of 2 noun
 * : a periodical publication
 * I'm not sure what "regularly" means, but if they're only published when there's something to announce, there could be times when several Announcement Letters are sent out and other times where nothing is heard from IBM in a while. Guy Harris (talk) 18:01, 9 June 2023 (UTC)
 * Did you not notice that I wrote that with a caveat: if you can convince yourself that the announcement letters are, in a sense, a form of periodical...? My experience with periodicals here at en.wiki, is that the periodical publishers do (usually) follow a schedule, but not always.  If you don't like  as a solution, don't use it.
 * —Trappist the monk (talk) 18:11, 9 June 2023 (UTC)
 * And I added some dictionary definitions to indicate that convincing oneself that the annoucnement letters are, in a sense, a form of periodical may be a mistake. What periodicals are published every time somebody has something to announce, and not published if they don't have something to announce?  What are some examples of "not always" that you have experienced? Guy Harris (talk) 19:15, 9 June 2023 (UTC)
 * Yes, I know why you added the definitions. Makes perfect sense to me to be silent when there is nothing to be said... To answer your not always question: usually its a case of combining multiple 'numbers' into a single issue.  Here are some search results looking for articles with multiple-numbers-in-a-single-issue (cirrus search so your results may be different):
 * – ~22,000 articles (timed out)
 * – ~5,300 articles (timed out)
 * – <100 articles
 * Not really uncommon. But, as I said before: If you don't like as a solution, don't use it.  I'm not arguing for or against the  solution; I'm happy with the  solution I demonstrated above.
 * —Trappist the monk (talk) 20:11, 9 June 2023 (UTC)
 * Not really uncommon. But, as I said before: If you don't like as a solution, don't use it.  I'm not arguing for or against the  solution; I'm happy with the  solution I demonstrated above.
 * —Trappist the monk (talk) 20:11, 9 June 2023 (UTC)

cite periodical is a redirect to cite magazine, which "is used to create citations for articles in magazines and newsletters".

The 1985 announcement letters were issued in batches, with varying numbers of letters in each batch, but there's not a completely clear schedule - one on Monday, 1985-12-30, several on Tuesday, 1985-12-17, one on Saturday, 1985-12-07, two on Thursday, 1985-12-05, a bunch on Tuesday, 1985-12-03, etc.. The recent announcement letters may be a bit more periodical in the schedule (weekly); the old search engine, if you search for all 2023 announcement letters, appears to cough up documents that aren't announcement letters, and the new search engine doesn't have an obvious way of searching by date, so I don't have better data.

So I am arguing against it, to the extent that I don't see any reason why anybody - not just me - should use it in this case. That comes across as an attempt to jam a square peg (an announcement letter) into a round hole (the category of "periodical").

I'm also not sure that the collection of all announcement letters constitutes a "work". The documentation for work in the cite web documentation says "Name of the work containing the source", which appears to say precisely nothing about what a "work" is. It lists "journal, newspaper, magazine, periodical, website", none of which appear to fit the collection of all announcement letters. If IBM issued a (somewhat-)periodical publication called "Announcement letters", with each issue containing a set of contemporaneous announcement letters, that might work, but if they just sent/send out each letter individually, it looks like another square peg/round hole pairing to me.

However, an announcement letter seems to fit in the same broad category as, for example, a press release, so type seems appropriate to me.

As for the template to use, if, as, and when cite document/new goes live, that seems the best choice, as it can handle announcement letters regardless of whether they're available online or not. Guy Harris (talk) 21:13, 9 June 2023 (UTC)

3O Response: This discussion was listed at Third opinion and I am commenting in response to that request. I have never edited this article before nor have I (to the best of my knowledge) interacted with either editor in any extended way, and am coming to the discussion as a neutral third-party. Reading over the discussion, the dispute seems to be twofold. It seems to be about the use of line breaks vs  and also about the correct parameter to be used when switching the soon-to-be inapplicable cite document (itself a current redirect to cite journal) with cite web. I'm not quite sure that this needs a third-opinion at this stage, but I've read too much of the discussion and ancillary pages, talk pages, and version histories to not comment now.

Regarding the line break code, there's no reason anyone would expect someone to know where to find this, but H:BR in the past advised that be preferred for technical reasons involving syntax highlighters and because browsers would just read all (valid) variations as  anyways (or possibly  but that level of technical granularity isn't really relevant now). That guidance was removed following this discussion in March 2023. Essentially, as long as it's not an invalid or similar and is just a difference between  and, its ultimately a matter of preference (though some editors have a strong preference). Until there's a consensus on guidance for one version over the other, I think it's fine to change it as part of a more substantial edit but it would be best to apply MOS:VAR and retain the original version if the change is disputed, unless there's a consensus for change.

As far as parameter usage, I think the discussion doesn't necessarily need additional input at this point since the template documentation is the guiding principal here and I think User:Trappist the monk's last comment about the usage of those parameters is a valid summation. Hopefully this outside opinion helps, and if additional comments are requested or I overlooked something critical please ping me in the comment so that I don't overlook it. Thank you. - Aoidh (talk) 00:19, 9 June 2023 (UTC)

Recovery
There are several issues in the description of recovery in #Evolution of MVS:

There is no mention of Associated Recovery Routines (ARRs), although that might be TMI.

Similarly, there is no mention of the STAI and ESTAI options of ATTACH.

A huge amount of privileged code in MVS runs in TCB mode and is allowed to use STAE and ESTAE.

Some program checks can be intercepted with SPIE and ESPIE, in which case no is no ABEND to recover from -- Shmuel (Seymour J.) Metz Username:Chatul (talk) 16:02, 6 February 2024 (UTC)