PoOP (-12 edition) states on page 4-47: For certain instructions, the TOD clock is considered to be extended to the left by an 8-bit epoch index. In a multiprocessing configuration, a single epoch index is shared by all CPUs. When the multiple-epoch facility is not installed in the configuration, the epoch index contains zeros when the TOD clock has not wrapped around to zero; when the TOD clock has wrapped around to zeros, it is unpredictable whether or not the epoch index contains zeros. When the multiple- epoch facility is installed in the configuration, the epoch index extends the capacity of the monotonic sequence of clock values to approximately 36,534 years.
But that is not the location I am asking about. I am asking about the LOW-order two bytes (the "Programmable Field"). Peter -----Original Message----- From: IBM Mainframe Discussion List <[email protected]> On Behalf Of Paul Gilmartin Sent: Wednesday, March 17, 2021 3:20 PM To: [email protected] Subject: Re: Contents of TOD Programmable Field under z/OS? EXTERNAL EMAIL On Wed, 17 Mar 2021 14:53:36 -0400, Brian Chapman wrote: >I may need wrong, but I seem to remember reading that the 12 bit lower >order value had some relation to the processor ID. This ensured the >STCK value would be unique across the sysplex. > The patent is no help: https://urldefense.com/v3/__https://patents.justia.com/patent/20030101365__;!!Ebr-cpPeAnfNniQ8HSAI-g_K5b7VKg!agRiorhCck5mAi2lTCG_ERgnTSnUGJMI0Sc4PUakKoE0EsD8S_V33ke2e0_B4pX9NIMoiw$ It never states, but one might infer that the high-order byte of ETOD might be incremented (by software?) when the clock wraps. >On Wed, Mar 17, 2021, 1:55 PM Farley, Peter x23353 wrote: > >> But is it documented anywhere? PoOP is silent on the value of the field. >> RCF needed. -- gil ---------------------------------------------------------------------- For IBM-MAIN subscribe / signoff / archive access instructions, send email to [email protected] with the message: INFO IBM-MAIN This message and any attachments are intended only for the use of the addressee and may contain information that is privileged and confidential. If the reader of the message is not the intended recipient or an authorized representative of the intended recipient, you are hereby notified that any dissemination of this communication is strictly prohibited. If you have received this communication in error, please notify us immediately by e-mail and delete the message and any attachments from your system. ---------------------------------------------------------------------- For IBM-MAIN subscribe / signoff / archive access instructions, send email to [email protected] with the message: INFO IBM-MAIN
