Re: What is PEP?

>Date: Fri, 16 Nov 2001 19:46:27 -0600
>From: Tadashi Kakefuda <tadashi@ff.iij4u.or.jp>
>
>I noticed that PEP itself was a kind of (a group of ?) internal object
>(s)(system program or procedure). It seems it calls a user program that
>we expected. IOW, it indicates the main program that you expected or a
>kind of bridge.... Am I right?
>
>When you execute CRTPGM A ...ENTMOD(B) and if you call program A,the
>Module B will be called (activated). Am I right?

In any module with a "main" procedure (for example an RPG module that
doesn't have NOMAIN, or a C module with a procedure called "main"), the
compiler also generates a special procedure called the PEP, whose job
(among possibly other things) is to call the actual main procedure,
passing the program parameters in a way the procedure can understand.
So the PEP is indeed a bridge between the system and the actual main
procedure.

When a program is created, all the PEPs are discarded except the one
for the ENTMOD module.

In your example, when you call program A, the system will call the PEP
for module B, and that PEP will call the main procedure in module B.
But all the modules in the program will be activated, and so will all the
modules in all the service programs used by the program (if they are not
already activated).  "Activated" means something like "having static
storage allocated and initialized".  (At least that's how I explain it
to myself.)

The only time you have to worry about the PEP is when you are sending
messages beyond the main procedure of your program.  You have to include
the PEP in your stack offset.

Barbara Morris