A user program written for MVS 3.8 runs without modification on z/OS. Features have been added, enhancements retain compatibility. BLKSIZE=0, SMS volume assignment, CVOL -> VSAM catalogs.
ISAM was already on way out, removed. TCAM is still 24 bit at unchanged since MVS 3.8 but still running on z/OS. (DOS/)VSE and JES3 sales and support now non-IBM. On Fri, Oct 31, 2025 at 2:04 PM Charles Mills <[email protected]> wrote: > Wait a minute ... > > Two flaws with the below. > > 1. MVS 3.8j is unsupported. Well, I suppose it is unsupported in the same > sense the Linux is unsupported -- the publisher, the owner of the IP > rights, does not support it. Third parties support it. I suppose if enough > companies ran MVS 3.8j there is no reason that a vendor could not come > along and provide support for MVS 3.8j, like Red Hat does for Linux. But I > still think you run into a massive "unsupported!!!" objection. > > 2. It's not just your compiled executable that has to fit into 16MB. It's > your compiled executable, all of the operating system components that it > needs direct addressability on, and all of its in-memory data ("buffers"). > For some applications that in-memory data could be voluminous. > > And maybe the IT industry is wrong to expect more than 16 MB but you don't > make sales by arguing with the customer. > > Charles > > On Fri, 31 Oct 2025 09:39:51 -0500, Paul Edwards <[email protected]> > wrote: > > >And MVS 3.8J can be run. Sure - you're restricted to 16 MiB - > >but - so what? Perhaps that's part of the problem with the IT > >industry - people expecting more than 16 MiB of memory. > > <snip> > > >The biggest actual executable with what I consider to be > >"genuine" code is gcc 3.2.3. It is 400,000 lines of C code, > >that translates into 700,000 lines of assembler code, and > >produces a 3 MB executable. Easily fits within 16 MiB. > > > >Is your startup going to produce a 400,000 line application? > > > >After how many decades? > > > >Can you even maintain that? What if you lose the one guy > >who can actually maintain that? > > > >By the time you get anywhere near that, I would expect you > >to have moved to genuine IBM hardware. > > > >My own code - written over 3 decades - and not completely > >alone - comes to something like 70,000 lines of code, and > >fits on a 360k floppy as main executables. > > ---------------------------------------------------------------------- > For IBM-MAIN subscribe / signoff / archive access instructions, > send email to [email protected] with the message: INFO IBM-MAIN > -- Mike A Schwab, Springfield IL USA Where do Forest Rangers go to get away from it all? ---------------------------------------------------------------------- For IBM-MAIN subscribe / signoff / archive access instructions, send email to [email protected] with the message: INFO IBM-MAIN
