COBOL Program performance tuning tips

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chaat
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Post by chaat » Mon Apr 20, 2015 7:35 am

I've had good results converting programs to be sort exit programs.

for example pgm 1 writes an output file A which is then sorted and the output is input to pgm 1

after converting pgm 1 to an E15 sort exit and pgm 2 to an E35 sort exit

three steps are replaced by a single sort step.

caveat... these programs are not incrementally restartable. the sort step must be run over again.

for large intermediate files the use of sort exit programs can dramatically reduce run time by eliminating I/O.
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dianaazura
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Post by dianaazura » Mon Jun 29, 2015 1:57 pm

if you are using INPUT/OUTPUT procedure then FASTSRT compiler option will not increase the performance.In such cases it is better to use the DFSORT control statements like INREC,OUTREC,SUM,SKIPREC,INCLUDE or OMIT ,STOPAFT etc and put them under the ddname SORTCNTL or IGZSRTCD. I had a situation where we loaded a large VSAM file into memory to be searched by online CICS application. We encountered problems trying to emulate the VSAM START verb using COBOL SEARCH ALL verb when the key does not exist in the array. To get around this we had to write our own BINARY SEARCH in COBOL.

William Collins
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Post by William Collins » Wed Jul 01, 2015 5:38 pm

If you have a look around here, you'll see chaat has also done the same with a hand-coded binary-search.

The COBOL compiler tells you if FASTSRT will impact your use of the COBOL SORT verb or not.

DFSPARM is a candidate for the additional control-cards for a FASTSRT data-manipulation, allowing the parms which are not available on the OPTION control statement.

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sridharmohan
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Post by sridharmohan » Mon Jul 16, 2018 3:45 pm

Does COBOL has a future scope?
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