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"DFSRRC00 vs IKJEFT01" for calling DB2-Cobol Programs

 
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arunsoods

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Joined: 13 Jul 2016
Posts: 11
Location: India

PostPosted: Fri Aug 12, 2016 9:54 pm    Post subject: "DFSRRC00 vs IKJEFT01" for calling DB2-Cobol Programs
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Hi Team,

In my project in all jobs I saw that we are calling COBOL-DB2 program using DFSRRC00 which is used to call IMS program.

I want to know:-
1) DFSRRC00 is more efficient for calling COBOL-DB2 program or IKJEFT01 in the respect of CPU time and cost.

Thanks and Regards
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Robert Sample

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Joined: 06 Jun 2008
Posts: 7905
Location: Bellevue, IA

PostPosted: Fri Aug 12, 2016 9:59 pm    Post subject:
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Do you have a performance issue at this time? If not, why on earth are you even thinking about the efficiency of DFSRRC00 versus IKJEFT01? Considering how fast modern machines are, you are unlikely to find any significant difference between them.
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arunsoods

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Joined: 13 Jul 2016
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Location: India

PostPosted: Sat Aug 13, 2016 2:31 pm    Post subject: Reply to: "DFSRRC00 vs IKJEFT01" for calling DB2-Cobol Programs
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Actually we are optimizing all our job. So I found that all our programs are COBOL-DB2 programs but still those jobs calling all modules using DFSRRC00. So i thought if we replace it with IKJEFT01, will it give some optimized results or not...??
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Robert Sample

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Location: Bellevue, IA

PostPosted: Sat Aug 13, 2016 7:43 pm    Post subject:
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Quote:
Actually we are optimizing all our job.
I assume you work for a contracting company attempting to pad its hours? The ONLY time with modern mainframes that anyone should want to optimize is AFTER a performance issue arises. See my signature for the Donald Knuth quote.

And what are you optimizing for? You could want to minimize CPU time? minimize elapsed time? (and no, those are not the same -- at all) minimize I/O? minimize tape usage? Saying you are optimizing without specifying what your goal is, means you're just wasting resources.

Furthermore, optimizing "all our job" (sic) is rather ridiculous. By the 80/20 rule, 20% of your jobs use 80% of whatever resource you are wanting to optimize -- so concentrate on them and ignore the other 80% since they make no material contribution to whatever issue you think you have that needs optimization to resolve. You could easily spend thousands in people time and testing time to save a few cents a job for those 80%.

And, finally, you may be chasing the end of the rainbow. If all your jobs are I/O-bound, and you are optimizing to minimize CPU time, then you have a MAJOR issue. Namely, with an I/O-bound job you could drop the CPU usage as close to zero as you want and it would not have any impact on the job as the critical path is the I/O, not the CPU. So unless you have analyzed your jobs, one by one, and know if they are I/O-bound or CPU-bound, even STARTING an optimization project is a huge waste of resources.

Have you TRIED replacing DFSRRC00 with IKJEFT01 in a job? What was the result if you did? If you haven't, why are you wasting time asking questions on a forum instead of actually testing things?

Optimization makes sense in a couple of cases -- where you have a known performance issue (such as the batch processing not completing in the batch window), or if your management wants to delay an upgrade by tweaking the current workload. However, in both cases the LAST place you look is individual jobs -- start by looking at the overall job flow and see if moving jobs around in the scheduler could buy back whatever is needed.
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Rohit Umarjikar

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Joined: 21 Sep 2010
Posts: 1609
Location: NY,USA

PostPosted: Mon Aug 15, 2016 8:49 am    Post subject:
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Major concentratation should be on SQL OR using proper indexes , the way you call or execute shouldn't matter much.Roberts signature should suffice that.
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arunsoods

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PostPosted: Mon Aug 15, 2016 10:56 am    Post subject:
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Thanks you so much team... icon_idea.gif
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