Thank you Jim, appreciate the detailed explanation which is understandably similar to Peter Relson's back in March.
My intent want not to take this thread in another direction, just thinking about PSF in terms of the poster's original question... On Wed, 19 Aug 2020 19:11:33 +0000 "Christopher Y. Blaicher" <cblaic...@precisely.com> wrote: :>We have a program that ran fine on a z13 that now gets an S0C4 on a z15. :>On a z13 we could access data in the PSA in the 2048 to 4095 range without going into key 0. The specific field is PSASVT. :>To get to that data now, we have to do a MODESET to key zero. :>Anyone else find this as a problem? Was it there with a z14? We jumped from a z13 to a z15. Thanks again, Mike -----Original Message----- From: IBM Mainframe Discussion List [mailto:IBM-MAIN@LISTSERV.UA.EDU] On Behalf Of Jim Mulder Sent: Wednesday, August 19, 2020 9:18 PM To: IBM-MAIN@LISTSERV.UA.EDU Subject: Re: Strange S0C4 on z15 Caution! This message was sent from outside your organization. The first machine to implement ESA/370 was the 3090E. This was done via microcode updates (since the 3090E hardware was designed prior to ESA). It was not possible to implement PSF in microcode, so MVS used x'1000' as the data space ORIGIN, Every subsequent machine (starting with the 3090S) implemented PSF, and MVS used 0 as the data space ORIGIN. That is still the case today, unless you specify HIDEZERO=YES on DSPSERV CREATE, in which case the ORIGIN is x'1000' and page 0 is hidden, This is desirable because it avoids PER ZAD events, and gives you a 0C4 abend instead of incorrect results when you accidentally use a bad pointer value in the range 0-FFF. Jim Mulder z/OS Diagnosis, Design, Development, Test IBM Corp. Poughkeepsie NY "IBM Mainframe Discussion List" <IBM-MAIN@LISTSERV.UA.EDU> wrote on 08/19/2020 07:01:09 PM: > From: "Mike Hochee" <mike.hoc...@aspg.com> > To: IBM-MAIN@LISTSERV.UA.EDU > Date: 08/19/2020 09:07 PM > Subject: Re: Strange S0C4 on z15 > Sent by: "IBM Mainframe Discussion List" <IBM-MAIN@LISTSERV.UA.EDU> > > Some months ago I asked a question regarding the relevance of the > ORIGIN parm on a DSPSERV macro. During that time I came across older > documentation which referred to low-address protection being in effect > when the PSF (Private Space Facility) was not active. My limited > understanding is that the PSF is active on 'virtually' all systems. > Mr Dissen's post below brought this to mind. > ---------------------------------------------------------------------- For IBM-MAIN subscribe / signoff / archive access instructions, send email to lists...@listserv.ua.edu with the message: INFO IBM-MAIN ---------------------------------------------------------------------- For IBM-MAIN subscribe / signoff / archive access instructions, send email to lists...@listserv.ua.edu with the message: INFO IBM-MAIN
