To save cost in batch programs

srebba · New User Joined: 26 Apr 2007 Posts: 37 Location: USA

Hi
I would like to know what kind of benfits we get if change below

'If program files are defined as "ACCESS IS DYNAMIC" and they're only being accessed sequentially, change them to "ACCESS IS SEQUENTIAL". Same holds true for files defined as "ACCESS IS DYNAMIC" and the access is purely random, change them to "ACCESS IS RANDOM".''

I would like to analyse my all batch programs and change if we get benfits.

Please let me know..

Thank you
Sree

Bill Woodger · Posted: Mon Aug 13, 2012 1:39 pm

Please don't tailgate an old topic.

Why don't you look at what the Cobol manuals have to say, and also try a couple of sample programs?

Robert Sample · Posted: Mon Aug 13, 2012 2:30 pm

Merely changing the ACCESS clause in the program will save little, if anything, since that clause is mostly for COBOL and has little or no run-time impact.

Managing buffers, which requires JCL changes, on the other hand can make a big difference especially if your site does not use vendor software to do so and your site uses the default buffering.

Ed Goodman · Active Member Joined: 08 Jun 2011 Posts: 556 Location: USA

Reading suggestion: VSAM Demystified. It's an IBM Redbook. That will tell you a lot of what you need to know. I'm pretty sure it's been kept updated, but make certain the specs match what your site is running.

You can get huge benefits in programs that are i/o bound on the VSAM files, but it's more than changing the access type. As said before, you need to also increase/improve the amount of read buffers the program can access.

dick scherrer · Posted: Mon Aug 13, 2012 8:59 pm

Hello,

Not to say the obvious, but you first need to identify whicn processes are using "too much" system resources. Then address the worst offenders first.

These may be vsam. sequential, and/or database processes. Each requires a different king of "tuning" - but first (imho) identification of where to get the best return on the improvement work.