On Tue, Apr 3, 2018 at 1:52 PM, Paul Gilmartin < 0000000433f07816-dmarc-requ...@listserv.ua.edu> wrote:
> On Tue, 3 Apr 2018 13:31:02 -0500, Tom Marchant wrote: > > > >... OS/VS1 and > >OS/VS2 release 1 were both introduced in 1972 and OS/VS2 release 2 (MVS) > >in 1973, though I don't know when it actually shipped. > > What was OS/VS2 without MVS? To me: > > OS/VS1 means a single large (up to 24-bit address limit) address space. > MVS means multiple address spaces, (each up to 24-bit address limit). > Not exactly correct. OS/VS1 was a single large address space. That one address space was divided up into a _fixed_ number of _fixed sized_ partitions (not regions). That is, if you had a step which required, say, 128M to run, you had to be sure it as in a partition which was at least 128M. The size of a partition was set by the sysprog or, IIRC, via an operator command. OS/VS2 release 1 was also called SVS (Single Virtual Storage). It has a single 24 bit addressable space which has a number of "regions" defined. Like in MVT, the size of a region was variable and basically it was "GETMAIN'd" when the job (or step - I forget) started. One problem that could exist in SVS was that a long running job might be GETMAINd while some smaller jobs were running. The long running job's storage would be a "sandbar" which could prevent other large jobs from running due to lack of contiguous storage. That why many shops would "shut down" batch in order to "start up" all the long running tasks, such as CICS, IMS, etc so that those STCs would not turn into storage sandbars. > > How does OS/VS2 before MVS fit in this picture? > > >See > >http://bitsavers.trailing-edge.com/pdf/ibm/370/OS_VS2/ > Release_2_1973/GC28-0667-1_OS_VS2_Planning_Guide_for_Release_2_Nov73.pdf > > -- gil > > ---------------------------------------------------------------------- > For IBM-MAIN subscribe / signoff / archive access instructions, > send email to lists...@listserv.ua.edu with the message: INFO IBM-MAIN > -- I have a theory that it's impossible to prove anything, but I can't prove it. Maranatha! <>< John McKown ---------------------------------------------------------------------- For IBM-MAIN subscribe / signoff / archive access instructions, send email to lists...@listserv.ua.edu with the message: INFO IBM-MAIN
