COBOL Quest

>>> If RPG programs call COBOL programs, there can be a performance
penalty. We
saw this in an RPG batch job, which called a COBOL progfram repeatedly.
Performance went from 10+ HOURS to <20 MINUTES, with one simple change. We
added a COBOL program as the first program. All it did was call the
original
first program in the batch job, but it does some smoke & mirrors stuff
.......

No "smoke and mirrors" - it's simply that COBOL programs run within what is
known as the Run Unit.  This is created by the first COBOL program that is
called in the job (if you mix OPM and ILE it's a bit more complicated but
.... ).  According to the ANSII rules for COBOL, if the first program in the
run unit (known as the Main program) returns to it's caller then the run
unit ends - this also has the effect of closing files etc. so it can cause
even bigger performance problems than the one you witnessed.



So, if an RPG program calls a COBOL program which then returns - the run
unit is created on the call, and destroyed on exit - that's a lot of wasted
time.  ILE programs have a mechanism that allows them to avoid this, but
for OPM the only answer is the one you used - put a "stub" program
somewhere in front of the RPG program that calls the "real" COBOL one.
That ensures that the run unit is maintained.



Jon.Paris@halinfo.it


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