Re: Checking if a program is active

> Checking only the invocation stack of all jobs is inadequate, because
> in OS/400, programs such as RPG can "exit" with LR=OFF, thus'
> staying "active", or in MI assembler terms, they can return or exit
> without issuing DEACTPG.  In that case, these programs are still
> "activated" (as in, activation groups, whether we are talking about
> the "default activation group" for OPM *PGMs, or some "named"
> activation group for ILE *PGMs and *SRVPGMs.

Unfortunately even if you deactivate a program that won't stop it from being
called again after being renamed.  Because the calling program may have
resolved a pointer to that renamed program so it will keep calling it using
that pointer.

I don't know of any safe way of deleting a program because you can never be
sure of the above situations.  The safest way it to put the old program in
QRPLOBJ then wait for the next IPL to erase it.

My 'Programs in Use' tool was designed to overcome the problem of having
duplicate processes running, or from preventing clashing applications
running out of sequence.  E.g. if the Invoicing program should not run while
Order Entry programs are active.  These are common problems on some ERP
packages.

> Unfortunately, IBM does not yet provide any APIs or any other
> documented way to find these "activated" *PGMs, that I am aware
> of, without going "below the MI".

Probably the only thing they could have done is put *SHRRD locks on active
programs.  But I suspect this would cause unacceptable overheads on program
calls.  So they didn't do it.  I can't remember whether it was done on
System 36/38.