>Question What if there is a CPU switch in the routine >being protected by the FRR
As Binyamin wrote, FRRs are processor-related. There is a stack. The obvious inference is that if a work unit is undispatched the stack must be saved. It is. When the work unit is redispatched, whether on the same or a different processor, the stack must be restored. It is. >Question I thought PC routines are protected by a ARR PC routines entered in task mode with no locks held and enabled for I/O and external interrupts *may* be protected by an ARR. ARRs protect only PC routines. Those two statements do not imply that PC routines *are* protected by an ARR or that they cannot be protected by some other kind of recovery routine (including ESTAEX or IEAARR, both of which are ESTAE-type).. >if EUT FRR are per TASK how does the Z/OS know they are >the secondary since all FRR's are Created by SETFRR Each work unit has an FRR stack. A work unit runs on one processor at a time. As discussed earlier, upon dispatch the work unit's FRR stack is moved to processor-related storage. Upon undispatch the work unit's FRR stack is copied from that storage to work unit-related storage. >there are TCB flags that indicate their presence. No there are not. But there is a pointer in the TCB to the area that contains the saved FRR stack for the task. Similarly, there is a pointer associated with an SRB to the area that contains the saved FRR stack for the SRB. Peter Relson z/OS Core Technology Design ---------------------------------------------------------------------- For IBM-MAIN subscribe / signoff / archive access instructions, send email to lists...@bama.ua.edu with the message: GET IBM-MAIN INFO Search the archives at http://bama.ua.edu/archives/ibm-main.html
