I know of a product that created a permanent subtask in the *MASTER* address space by scheduling an SRB to *MASTER*, which then located the IEEVWAIT task there and issued CIRB to create an IRB associated with IEEVWAIT, which in turn issued an ATTACH to create a permanent subtask of IEEVWAIT. The technique was used to create a task that would write SMF records asynchronously out of *MASTER*, and it worked well.
Mike Shaw MVS/QuickRef Support Group Chicago-Soft, Ltd. On Sun, Sep 17, 2023 at 10:09 AM Seymour J Metz <[email protected]> wrote: > An IRB is an RB while an SRB, despite the name, is not. An SRB oes away > once it is dispatched; a page fault schedules a new SRB to resume once the > page is read in. > > GY28-6659-7, OS Release 21. 7 - IBM System/360 Operating System - MVT > Supervisor - Program Number 360S-CI-535, GY28-6659-7, SERVICES INDIRECTLY > RELATED TO A TASK > CONTROL BLOCK, pp. 43-44, at < > https://bitsavers.org/pdf/ibm/360/os/R21.7_Apr73/plm/GY28-6659-7_MVT_Supervisor_PLM_Rel_21.7_May73.pdf#page=63> > and SCHEDULING A USER EXIT ROUTINE, pp. 64-67 at <...#page=84>, provides a > good description that is till relevant to z/OS, although some details have > changed. > > ________________________________________ > From: IBM Mainframe Discussion List <[email protected]> on behalf > of Tom Brennan <[email protected]> > Sent: Sunday, September 17, 2023 1:58 AM > To: [email protected] > Subject: Re: Why it's important to take Seymour's advice > > I've never written code that runs as an SRB, but over the years I've > read about them and seen them in action, such as Omegamon poking code > into other address spaces to grab data or do things like zap memory. So > my simple understanding is an SRB is code that once scheduled, gets run > first when the dispatcher comes back around to that address space, and > then (I assume) is removed once it has done its work. > > So what's an IRB - Interrupt Request Block? I've heard the name but > know nothing about it other than the manual mentions Asynchronous Exits, > but doesn't seem to go into the details. So are we talking about code > that gets executed sometime during interrupt processing, such as when an > I/O interrupt occurs? > > On 9/15/2023 10:54 PM, Michael Stein wrote: > > On Fri, Sep 15, 2023 at 06:16:59PM -0400, Joseph Reichman wrote: > >> I did schedule the irb in the ikjeft01 TCB against Seymour's advice > >> for a return code of zero from schedirb > > > > There are likely many ways to do something like what you are trying > > to do and the IRB idea likely wasn't close to the best, however: > > > > * if you have a test system at your disposal where a dump or crash > > won't hurt others > > > > * and you have the time to do a bit of exploring and learning > > > > I don't see it as bad, unless you don't learn from it. > > > >> However the TMP Estae issued an SDUMP > > > > Which is what I'd expect if the code the IRB tried to run had any sort > > of problem (program check? abend?). The resulting abend will be passed > > to that tasks (IKJEFT01) ESTAE and most likely it has no idea what to > > do about it. So it took a dump and likely got the RB chain for that > > task cleaned up (or terminated the task?). > > > >> I guess it didn't like me scheduling an irb in its TCB > > > > No, my best guess is that IKJEFT01 has no idea anyone would do such > > a thing. And if the IRB code ran and terminated normally the IRB would > > go away and IKJEFT01 would still be there and would never know. > > > > Go read the dump and figure out what happened... > > > > Find the IJKEFT01 TCB and it's RB chain. Does it show an IRB on the > > chain? Where do the PSWs in the RBs on the chain point? > > > > ---------------------------------------------------------------------- > > For IBM-MAIN subscribe / signoff / archive access instructions, > > send email to [email protected] with the message: INFO IBM-MAIN > > > > > > ---------------------------------------------------------------------- > For IBM-MAIN subscribe / signoff / archive access instructions, > send email to [email protected] with the message: INFO IBM-MAIN > > ---------------------------------------------------------------------- > For IBM-MAIN subscribe / signoff / archive access instructions, > send email to [email protected] with the message: INFO IBM-MAIN > ---------------------------------------------------------------------- For IBM-MAIN subscribe / signoff / archive access instructions, send email to [email protected] with the message: INFO IBM-MAIN
