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June 2004, Week 2

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Subject:
From:
Walter Murray <[log in to unmask]>
Reply To:
Walter Murray <[log in to unmask]>
Date:
Thu, 10 Jun 2004 00:05:09 -0500
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 "Shahan, Ray" <[log in to unmask]> wrote:
>In an effort to squeeze out every last drop of 'oomph' from the 3k, we're
reviewing some of the
>existing programs to see if we can do anything to increase their
performance.  One thing that I noticed
>in some of the programs is that they have very large internal arrays (one
prog has two separate arrays
>that both have 9999 elements).  In the past, I've always used the DEPENDING
ON phrase to
>dynamically allocate the elements as required (and to downsize the array
when the elements were no
>longer needed).

>I have been told that using the depending on phrase no longer matters since
MPE (via the COBOL
>compiler?) will allocate the space required for the upper limit of the
array's size regardless of what the
>array size variable contains.  I searched the archives, but did not see the
answer for this, so does
>anyone out there have the definitive answer?

When I attended my first meeting of J4 (the COBOL standards committee),
everybody was talking about ODO tables.  It took me a while to figure out
that ODO stood for "Occurs Depending On".

I can't speak definitively, but, based on my recollection of the internals
of the HP COBOL compiler, I can't think of any situation where the compiler
would allocate less then the maximum size of the table.

If I used an ODO table, it would be mostly for stylistic reasons, or to try
to make the code cleaner and clearer.  I wouldn't expect any performance
advantage.

Walter

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