0 was the address of the restart new PSW in ESA/390. When we implemented zArchitecture 20 years ago, we set the obsolete ESA/390 interrupt new PSWs such that if someone tried to simulate an interrupt by doing a LPSW for one of them, the result would be a 0E1 wait state with a unique reason code. We figured that after 20 years of that, we had already gotten whatever value that there might have been from that, and it might now be better not to have things like 000A0000 and 000130E1 hanging around down there where some program that has a null pointer bug might pick them up and end up trying to use them as addresses and get into even more weird results or storage overlays (since those are often valid GETMAINed addresses). So in z/OS 2.5, we changed those back to being reserved fields that are initialized to zeroes.
Jim Mulder z/OS Diagnosis, Design, Development, Test IBM Corp. Poughkeepsie NY "IBM Mainframe Discussion List" <[email protected]> wrote on 11/24/2021 05:58:15 PM: > From: "Hank Oerlemans" <[email protected]> > To: [email protected] > Date: 11/24/2021 07:57 PM > Subject: PSA 0 > Sent by: "IBM Mainframe Discussion List" <[email protected]> > > A random neuron thinks there was an announcement but if anyone can > shed some light I'm curious about Address 0. > > I am used to seeing X'000A0000' then X'000130E1' in the first 8-bytes. > This is no longer so. All zeros. A good thing ! > > SA22-7832-12 of Pops doesn't mention anything in CH. 3. > > So was there any kind of announcement for z/OS 2.5 ? ---------------------------------------------------------------------- For IBM-MAIN subscribe / signoff / archive access instructions, send email to [email protected] with the message: INFO IBM-MAIN
