On Tue, 14 Sep 2010 10:26:30 -0500, McKown, John <john.mck...@healthmarkets.com> wrote:
>> -----Original Message----- >> From: IBM Mainframe Discussion List >> [mailto:ibm-m...@bama.ua.edu] On Behalf Of Paul Gilmartin >> Sent: Tuesday, September 14, 2010 10:23 AM >> To: IBM-MAIN@bama.ua.edu >> Subject: Re: z/OS V1.12 differences and z196 (the new >> mainframe) impacts >> >> On Tue, 14 Sep 2010 11:04:47 -0400, David Cole wrote: >> >> >> >>Except for regs 0,1,15 your assertion is true. >> >> >> >>The high halves of those regs are not preserved across any interface >> >>unless otherwise documented. >> > >> >This is in contradiction to a verbal statement he made at a >> >presentation several years earlier wherein he flatly stated that no >> >preexisting AMODE(24/31) program would ever behave differently (due >> >to the widening of the registers) when run in z/OS vis-a-vis OS/390. >> >Unfortunately, I don't have "the video". >> > >> Ah, semantics! Can a program run in AMODE(24/31) in OS/390 >> (in a supported configuration) and use grande registers? >> >> -- gil > >Sure. Why not. I use them for 64 bit numbers where I used to use a register pair. Can OS/390 run on z hardware? I don't remember anymore. But use of Grande registers in application code cannot be stopped by the OS. Of course, if you call other routines, you'd better store them yourself. Because somebody else might be doing the same. In this context, John, it seems to me that "pre-existing" means "before 64-bit registers existed", and thus your programs that use 64-bit registers don't count. Pre-existing programs would only use 32-bit registers, and would not have any knowledge of the high-halves of the 64-bit registers, and are not affected by this change. -- Walt Farrell IBM STSM, z/OS Security Design ---------------------------------------------------------------------- For IBM-MAIN subscribe / signoff / archive access instructions, send email to lists...@bama.ua.edu with the message: GET IBM-MAIN INFO Search the archives at http://bama.ua.edu/archives/ibm-main.html
