On Sun, 17 Jul 2011 16:59:53 -0400 michealbutz <[email protected]> wrote:
:>FRR information is stored off of PSA - not in any task related block. :>Statement. As opposed to a SCB Thus the routine FRR can be called by a SRB or TCB since :>PSA is :>related to the CPU :> Question What if there is a CPU switch in the routine being protected by the FRR If locked or disabled there ain't no CPU switch. The unit of work does not lose control (if there is a program check, the FRR gets control which is the same unit of work). :>When DAS came out (MVS/SP1.3) ESTAE could not operate in other than :>primary=home=secondary. The only way a PC routine could do recovery was thru :>an FRR. Rather than require that these routines get a lock to be protected, a :>secondary FRR stack was created and a bit in PSA that indicated that an EUT :>FRR stack was active. Then, if there is a task switch, the EUT FRR stack is :>saved and restored upon redispatch. :>Question I thought PC routines are protected by a ARR Young grasshopper, the ARR is a relatively new invention. I doubt that it was even in XA. ESA, with access registers, made things easier. :>Question Going back to the first comment if EUT FRR are per TASK how does the Z/OS know :>they are :> the secondary since all FRR's Are Created by SETFRR If SETFRR is issued with EUT=YES and EUT is required since this is an enabled user task a bit is set in the PSA indicating that EUT is active and thus the FRR stack is saved upon CPU switch. -- Binyamin Dissen <[email protected]> http://www.dissensoftware.com Director, Dissen Software, Bar & Grill - Israel Should you use the mailblocks package and expect a response from me, you should preauthorize the dissensoftware.com domain. I very rarely bother responding to challenge/response systems, especially those from irresponsible companies. ---------------------------------------------------------------------- For IBM-MAIN subscribe / signoff / archive access instructions, send email to [email protected] with the message: GET IBM-MAIN INFO Search the archives at http://bama.ua.edu/archives/ibm-main.html
