Fwd:RE: Mysterious MCH3601 errors at V4R3M0

[Eric Sundell PMI <esundell@xxxxxxxxxxxxx>]

____________________Forward Header_____________________
Subject:    RE: Mysterious MCH3601 errors at V4R3M0
Author: "bmorris@ca.ibm.com" [SMTP:bmorris@ca.ibm.com]
Date:       8/11/99 10:41 AM

Dave, the APIs have 2 kinds of optional parameters: "optional" and
"omissible".
The optional ones are truly optional and can be left out of the call
entirely.
The omissible ones have to be coded on the call; all "omissible" means is
that
you can pass a null-pointer to them; in RPG terms, this means passing *OMIT.
If
you use prototyped RPG calls, when the API says "optional", code
OPTIONS(*NOPASS); if it says "omissible", code OPTIONS(*OMIT).

If you leave out an omissible parameter, and there happens to be a valid
pointer
where the API looks for that parameter on the stack, it will update the
storage
that the pointer is pointing to.  If it's a pointer to read-only storage, it
can
result in a storage violation (and you're lucky); otherwise, "some" storage
will
get corrupted.

Since pointers get "on the stack" from previous calls, the actual storage
that
gets corrupted will depend on what calls were made prior to the call that is
causing the problem.  Depending on the number and nature of the parameters
to
those calls, it might be several calls back, and who-knows-what is going to
get
corrupted.

In short, the answer to your question is "yes" :-)

Barbara Morris

>Date: Wed, 11 Aug 1999 09:35:35 -0500
>From: "Leland, David" <dleland@Harter.com>
>Subject: RE: Mysterious MCH3601 errors at V4R3M0
>
>Well, that could explain my problem.  I'm using CEEDOD and only passing
>in the 6 required parameters.  Do I need to pass in *OMIT for the
>seventh parameter which is omissible?.
>
>Thanks,
>Dave


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