It's called z/OS is not the only thing that runs on a 64-bit machine. I haven't looked into all the particulars, but I have heard someplace that 'C' can run in 64-bit under z/LINUX.
I think this is more a case of not wanting to have to re-write half of the operating system and have dual API's for everything when it isn't needed. At least not yet. Because they have done some work in that direction, it seems to me they are taking small deliberate steps to get there. I know nothing as fact, just a lot of looking at the tea leaves. Chris Blaicher Technical Architect Mainframe Development Syncsort Incorporated 2 Blue Hill Plaza #1563, Pearl River, NY 10965 P: 201-930-8234 | M: 512-627-3803 E: cblaic...@syncsort.com www.syncsort.com CONNECTING BIG IRON TO BIG DATA -----Original Message----- From: IBM Mainframe Discussion List [mailto:IBM-MAIN@LISTSERV.UA.EDU] On Behalf Of Charles Mills Sent: Monday, March 27, 2017 6:11 PM To: IBM-MAIN@LISTSERV.UA.EDU Subject: Re: 64 bit execution above the bar The fact that the hardware guys and gals made the hardware capable of execution above the bar means IBM is giving this some thought. (The thought may be "Heck, no!" <g>) Charles -----Original Message----- From: IBM Mainframe Discussion List [mailto:IBM-MAIN@LISTSERV.UA.EDU] On Behalf Of Paul Gilmartin Sent: Monday, March 27, 2017 5:00 PM To: IBM-MAIN@LISTSERV.UA.EDU Subject: Re: 64 bit execution above the bar On Mon, 27 Mar 2017 15:19:31 -0500, Dave Anderson wrote: >What is IBM's strategy for migrating code execution to be above the bar? Has >IBM released any documents detailing the next steps, or is this confidential? > It has been discussed here for a while. You could disable interrupts, branch to code above the bar, and branch back later. (I suppose the Old PSW was unconditionally scrunched.) More recently, interrupts above the bar are tolerated, but no system services can be called from above the bar. >Currently data areas above the bar are widely used but program execution above >the bar is not currently supported. Other posts have suggested that Cobol will >soon support 64 bit execution but not only for modules loaded below the bar >and that 64 bit Cobol is unlikely to be widely used as it is not compatible >with 31 bit Cobol and has performance issues. > Performance issues have been mentioned here. Are those because of: o I-fetch bandwidth? o Address calculation/translation overhead? o Computation overhead? o Some combination? I'd guess that instructions with 64-bit operands are slower than instructions with shorter operands, even in AMODE 24/31. Is AMODE 31 slower than AMODE 24? (Or even the opposite?) >Does anybody know if IBM plans to run system modules above the bar? I would be >interested in hearing any comments/insights on this topic? > Not I. How close is LPA to encountering a Virtual Address Storage Constraint? ---------------------------------------------------------------------- For IBM-MAIN subscribe / signoff / archive access instructions, send email to lists...@listserv.ua.edu with the message: INFO IBM-MAIN ________________________________ ATTENTION: ----- The information contained in this message (including any files transmitted with this message) may contain proprietary, trade secret or other confidential and/or legally privileged information. Any pricing information contained in this message or in any files transmitted with this message is always confidential and cannot be shared with any third parties without prior written approval from Syncsort. This message is intended to be read only by the individual or entity to whom it is addressed or by their designee. If the reader of this message is not the intended recipient, you are on notice that any use, disclosure, copying or distribution of this message, in any form, is strictly prohibited. If you have received this message in error, please immediately notify the sender and/or Syncsort and destroy all copies of this message in your possession, custody or control. ---------------------------------------------------------------------- For IBM-MAIN subscribe / signoff / archive access instructions, send email to lists...@listserv.ua.edu with the message: INFO IBM-MAIN
