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Question about DD DUMMY

 
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kumar1234

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Joined: 06 Nov 2007
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PostPosted: Thu Jul 10, 2008 6:52 pm    Post subject: Question about DD DUMMY
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Can anyone help me understand this JCL syntax? Will it have some records or not, if dummy then why is DCB given?

//Q105PRT DD DUMMY,DCB=(RECFM=FBA,LRECL=133,BLKSIZE=3990)


Thanks,
Kumar.
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expat

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PostPosted: Thu Jul 10, 2008 6:57 pm    Post subject:
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Well, take a look at your DD statement. If the file is output where would the records be written to, and if it is input, from which file will the data be read from. In both cases the answer is the same - no file specified.

DCB is usually picked up from the catalog entry of the dataset if input, or defined in the DD statement if output. In the case of input dummy file;, there is no filename to get the catalog information from, hence the need to define it.
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Bill Dennis

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PostPosted: Thu Jul 10, 2008 7:03 pm    Post subject:
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expat wrote:
DCB is usually picked up from the catalog entry of the dataset if input....
The DCB info is more often found in the tape header label or DASD VTOC entry for a file. Only VSAM files have record length info in the catalog.
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kumar1234

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PostPosted: Thu Jul 10, 2008 7:11 pm    Post subject: Reply to: Doubt in DUMMY
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Thanks for this valuable info........
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mmwife

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PostPosted: Fri Jul 11, 2008 6:44 pm    Post subject:
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As I recall, if the DUMMYed file is O/P and the pgm has not specified the minimum DCB info (usually w/Assembler pgms) the pgm will abend or issue a bad status code if the DD card doesn't contain the LRECL.
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