>Now STC39500 looks like some sort of started task that began like this:
> BPXP024I BPXAS INITIATOR STARTED ON BEHALF OF JOB FTPD9 RUNNING IN ASID
> 01C1
Don't get fooled by that stupid message. It may have been introduced for some
debugging purposes, I can't tell.
What is an address space called BPXAS? It is an idle initiator waiting for some
UNIX work to arrive it can host.
New UNIX processes that result from (non-local) spawn() or fork() function
calls need an address space to run in. Because creating as well as destroying
an address space is somewhat costly in z/OS and because many UNIX processes are
very short living (think of shell commands as an example), BPXAS initiator
address spaces were invented back in OS/390 V1.3 (or around that time. Before
that APPC initiators have been "missued" for this).
Step 1) When a new process needs an address space, the system looks if it can
find an *idle* BPXAS initiator.
Step 1a) If so the process' environment will be built in that existing
BPXAS address space and the process can run.
Step 1b) If no idle BPXAS is available (and WLM thinks the system can
cope with one more address space), then a new BPXAS is started for this new
process, the process' environment will be built in the newly started BPXAS
address space and the process can run.
Step 2) When the process finally ends, the address space is no longer needed
and could be destroyed. Again, since this is somewhat costly, the BPXAS
initiator AS will not immediately end. It will stay around for 30 minutes (this
30 minute period was a hard coded; I believe it still is), and will be
available for step 1/1a of another new process. Chances are, a new process will
be born in due time (if there is some UNIX work going on on that system).
I don't know when the above message has been introduced (it wasn't always
there), but the message is issued *once* when a new BPXAS is started (Step 1/1b
above). It documents the jobname and ASID of the *parent* process, i.e. the
process that initiated the new process about to be run in this BPXAS.
Thereafter, no message is issued when an existing, idle BPXAS is selected to
host just another process.
--
Peter Hunkeler
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