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meaning of BLOCK CONTAINS 0 RECORDS

 
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raviprasath_kp
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PostPosted: Tue Aug 21, 2007 8:39 pm    Post subject: meaning of BLOCK CONTAINS 0 RECORDS
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any one can suggest me why we are using
BLOCK CONTAINS 0 RECORDS
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dbzTHEdinosauer

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PostPosted: Tue Aug 21, 2007 8:45 pm    Post subject:
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on new versions (the old, also), the system can calculate the optimum blocksize for a DASD device better than the programmer. It is considered a 'Best Practice'.
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dr_te_z

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PostPosted: Wed Aug 22, 2007 11:09 am    Post subject:
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Yep, it's called "SDB" (system determined blocksize). You code your application like you described, do not hard-code blocksizes in your JCL and the O.S. will determine the optimum blocksize for you, taking into account the DADS device on which the dataset is placed.

I worked in a componay once which had a mix of 3380 en 3390 disks. Works very cool.

1 catch: when you concatinate input datasets, you have to make sure they all have the same blocksize (so be sure there placed on the same type of DASD).
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Anuj Dhawan

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PostPosted: Wed Aug 22, 2007 11:34 am    Post subject:
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Hi,

Bit more:

When running under MVS, BLOCK CONTAINS 0 can be specified for QSAM files; the block size is determined at object time from the DD parameters or the data set label.

The BLOCK CONTAINS clause is an optional clause in a file description entry. The BLOCK CONTAINS clause specifies the size of the physical records. The characters in the BLOCK CONTAINS clause reflect the number of bytes in the record. (For example, if you have a block with 10 DBCS* characters, the BLOCK CONTAINS clause should say BLOCK CONTAINS 20 CHARACTERS.

*Double-Byte Character Set

Hope this helps.
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