Might it have been different before page 0 was protected and the first half unprotected via Fetch-Protection-Override Control?
Before that page zero could not be fetch protected. On Mon, 4 May 2026 06:25:43 +0000 Jim Mulder <[email protected]> wrote: :> You are correct. I will submit a documentation update request. Originally, CALLDISP BRANCH=YES referenced CVT0DS, not the SVT. It changed :>to use the SVT fields in MVS/370 SP1.2 ( around 1980). However, even prior to that, CVT0DS pointed to entry point IEA0DS in module IEAVEDS0, and in the MVS 3.8 code, :>that would have gotten a 0C4 abend trying to store into the PSA if not running in PSW key 0. So CALLDISP BRANCH=YES has apparently always required PSW key 0 (at least in MVS - I don't :>know if there was a CALLDISP in OS 360 - that is too far before my time and I don't have source code from that era). :> :>Jim Mulder :> :>-----Original Message----- :>From: IBM Mainframe Discussion List <[email protected]> On Behalf Of Binyamin Dissen :>Sent: Sunday, May 3, 2026 9:23 AM :>To: [email protected] :>Subject: Using CALLDISP BRANCH=YES,FIXED=NO :> :>Doc states: :> :>When BRANCH=YES :> :>Minimum authorization: When FIXED=NO: Supervisor state or PKM allowing key 0 When FIXED=YES: Supervisor state and PSW key 0 :> :>But the code expands to :> :> + L 15,PSASVT-PSA(0,0) (00000B4C) :> :>which is in key0 fetch protected storage. :> :>KEY0 is required. -- Binyamin Dissen <[email protected]> http://www.dissensoftware.com Director, Dissen Software, Bar & Grill - Israel ---------------------------------------------------------------------- For IBM-MAIN subscribe / signoff / archive access instructions, send email to [email protected] with the message: INFO IBM-MAIN
