Re: MCH3601 errors

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Hello David,

You wrote:
>I've got a particularly perplexing problem with a MCH3601 exception.
>I understand that this error is often caused by a missing, or incorrectly
>specified, parameter on a program call.  Unfortunately, I can't figure out
>where the parameter error is.  I've looked at everything near the failure
>point, both RPG and CL, and everything jives with the docs.

A pointer is NULL.  It might be a program parameter that was not passed to this 
program.  It could also be a basing pointer that is not set (or that gets set 
to 
NULL).  It can also be caused by initially defining a procedure (in a service 
program) to use VALUE and then changing the prototype to CONST, compile the 
program that invokes the procedure, but forgetting to rebuild the service 
program. (Ask me how I know :)

>Any suggestions on how to debug this?

I usually use debug to display the program parameters, any variables passed to 
another program or procedure, and any variables that seem likely candidates.

Display the message details and see what the sending and receiving procedures 
are.  Also the statement numbers in those procedures will help locate the area.

If that doesn't help then I write a sample program that does the minimum work 
and see if that works.  If it does then I add more of the original code until 
it 
breaks.

One other idea:  I have seen this error when calling a program that expected an 
EXPORTED variable to be available in an activation group but it wasn't 
available.  How can this happen?  The architected invocation is:
        PGMA (ACTGRP X) --> EXPORTS flag
                PGMB    (ACTGRP Y)
                        PGMC    (ACTGRP X) <-- IMPORTS flag

Now someone needs to call PGMC to do something and they try
        PGM1    (ACTGRP A)
                PGMC    (ACTGRP X)  == BOOM MCH3601

cause the imported flag variable ain't there.


Regards,
Simon Coulter.

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