Re: *PSSR subroutine and the call stack

[dhandy@xxxxxxxxxxx (Douglas Handy)]

Albert,

>When you use the *PSSR subroutine and specify *DETC on the ENDSR line, does
>the internal call stack get reset?

If I infer correctly what you are asking, you are expecting RPG to
push/pop instruction addresses on/off a call stack when executing
subroutines.  While most languages do so, RPG does not.  That is one
reason RPG actually lets you directly branch out of a subroutine to
detail calcs using GOTO/TAG.  It does not leave an unbalanced call
stack because nothing was pushed when the subroutine was called.
(This is also another reason subroutines can't support recursion.)

So if your concern is whether an unbalanced call stack condition
happens with *PSSR, the answer is no.  It should be noted that
subprocedures are different than subroutines -- subprocedures do use a
call stack and they support recursion.  But they have their own *PSSR
handling.  And the subprocedure's *PSSR needs to either do a RETURN or
brach back into the subprocedure where it will eventually do a RETURN.
Therefore, the call stack remains balanced here too. (Without a *PSSR,
a subprocedure percolates the exception to a condition handler, not
the mainline *PSSR.)

But maybe this isn't what you were asking, in which case never mind...

Doug
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