It seems I have not been clear enough.
Like a JESx initiator, which, in its lifetime, may serve as a container (address space) for many batch jobs, BPXAS initiators may, in their lifetime, serve as a container (i.e.address space) for many, many processes one after the other.
The message BPXP042I documents only which (parent) process initiated *the creation of this very instance of a BPXAS address space* because it (the parent process) started a new (child) process (via spawn() of fork()). Thereafter, the very same instance of the BPXAS address space may be used again and again and again. Each time a process does a (non-local) spawn() of a fork(), one such BPXAS is needed.
If a BPXAS is sitting around doing nothing, i.e. it is idle, this means it has been hosting one or more processes before. But currently, it is waiting for another process it can host, or, for the 30 minute idle period to expire. You will see message BPXP024I only for the *very first* process is was hosting in its lifetime.
In SDSF, when you see a line saying BPXAS, this is a line showing an *idle* "UNIX process initiator". This is equivalent to JESx initiators. When you see a line saying INIT, this is an idle batch job initiator.
The JESx initiator changes its displayed jobname when it is serving a batch job. Equally, a BPXAS changes its displayed jobname when it is serving a UNIX process.
>I have seen that message citing my own (TSO) userid as jobname. And I had certainly NOT done anything at that time. I had done something in OMVS before, though (like 5 minutes earlier). Is it possible that the jobname/userid somehow somewhere gets stored and reused despite *this* parent process being someone else? I have also seen this happen with IBMUSER, and the colleague doing the ftp swears that he didn't use IBMUSER for his ftp.
Let's assume you start your TSO session (your ID is BARBARA), then do something with Z/OS UNIX that starts a new UNIX *non-local* process. (There are processes that may run in the current address space, called local processes. There are processes that may *not* run in the current address space, called non-local processes.) Since this new non-local process needs an address space to run in, the system looks if it can find an *idle* BPXAS. We assume now, there was none, so a new one was started especially for you, well for your process. The system then writes message BPXP024I to document that your TSO session was the reason this BPXAS was started. (To be exact: The message documents that there is a process running in address space BARBARA that initiated this BPXAS creation. It does not say this is a TSO session.)
At this time (and before the process ends), you can see 2 lines in SDSF: One called BARBARA, a TSU line, representing your TSO session, and a second one called BARBARA1, an STC line, representing your UNIX process. You won't see a line called BPXAS.
Sometime later, your non-local process ends; the BPXAS becomes idle. You can again see it as BPXAS in SDSF and you can read message BPXP024I saying it was started for parent BARBARA.
Let's now assume nothing else happened on the system until 5 minutes later, when your colleage FOO performs the very same steps described above. The BPXAS is still idle and the system will select it to host Foo's UNIX process. Since the BPXAS was already running, *no* BPXP024I message is written.
At this time (before the process ends), you can see 2 lines in SDSF: One called FOO, a TSU line, representing Foo's TSO session, and a second one called FOO1, an STC line, representing Foo's UNIX process. You won't see a line called BPXAS.
Sometime later, Foo's non-local process ends; the BPXAS becomes idle again. You can again see it as BPXAS in SDSF and you can still read message BPXP024I saying it was started for parent BARBARA.
You won't see Foo's process mentioned. Why? Imagine, say, ten UNIX guys are logged into Z/OS UNIX working hardly in their shell environments for 8 hours. You can imagine that thousands and thousands of processes have been started and ended during that working day. Say, a couple of BPXAS address spaces could cope with the work but never got idle long enough (the 30 minutes period) to end. If BPXP024I was written for each and every process, there were thousands and thousands of BPCXP024I messages in those BPXASs filling your spool.
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Peter Hunkeler