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BLocksize calculation when its mentioned in COBOL/JCL

 
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niks_jude
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PostPosted: Wed Dec 12, 2007 1:14 pm    Post subject: BLocksize calculation when its mentioned in COBOL/JCL
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Suppose blksize parameter has been mentioned as 'A' in COBOL program for a dataset and 'B' in the JCL. And we are creating the dataset then what will be the blocksize of the dataset - 'B' or 'A' ? And what will happen if we mention the blocsize in COBOL program but as '0' in JCL-- Will the system go for creating an optimal blocksized dataset or will it take blocksize from the COBOL program?
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dick scherrer

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PostPosted: Wed Dec 12, 2007 10:47 pm    Post subject:
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Hello,

I suspect that you have received no replies because most folks expect you to test this on your system and post any questions you have about what happens.

Along the line of your question, it is a better practice to remove block size specifications from the cobol code as well as the jcl. You might talk with your storage administrators and ask what is preferred on your system.
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expat

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PostPosted: Thu Dec 13, 2007 12:19 am    Post subject:
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Don't use BLKSIZE=0 ..... it can cause problems if your SMS isn't set up correctly.

It can create datasets with a blocksize of 0 which are not processed by HSM.
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Douglas Wilder

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PostPosted: Thu Dec 13, 2007 4:54 am    Post subject:
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Under what conditions would BLKSIZE=0 not work correctly? What should we be using in place of BLKSIZE=0 to have the system calculate the best block size to use? I have been using it for years at several clients. If there is something better to use please let me know.
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rpuhlman

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PostPosted: Thu Dec 13, 2007 5:22 pm    Post subject:
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In most shops I've been in ... omitting the BLKSIZE parameter altogether will allow the system to calculate the optimal block size for your dataset. Not sure whether that is an affectation of SMS or not ... since I'm not a sysprog.
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dick scherrer

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PostPosted: Thu Dec 13, 2007 10:13 pm    Post subject:
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Hello,

Quote:
I have been using it for years at several clients
Yes, for many years this was preferred (i believe it still is for non-SMS managed dasd).

As more and more of the dasd is sms-managed, completely removing the blksize from jcl is becoming (has become?) the preferred method.
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