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Empty KSDS Files


IBM Mainframe Forums -> JCL & VSAM
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Jeenu Bajaj

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Joined: 20 Aug 2015
Posts: 3
Location: Gurgaon

PostPosted: Fri Aug 21, 2015 2:44 pm
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I have 2 KSDS Files, One which I deleted defined and it contains No Records. And the other KSDS File, from which I deleted all the records.

There is a difference in these 2 files, Can anybody please let me know what it is.
When i am browsing the first one, I am not able to browse it, it says Empty File. But I can browse the second file, although that also does not have any record. I tried giving the 2 files in JCL as input. For first one, JCL fails with file status code 35, as we all know we can not open empty VSAM file for input. But with Second type of file, JCL runs smoothly without giving any error
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Bill Woodger

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Joined: 09 Mar 2011
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PostPosted: Fri Aug 21, 2015 3:50 pm
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To be opened successfully for reading, a KSDS must have had at least one record written to it, even if it currently contains no records.
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Jeenu Bajaj

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PostPosted: Fri Aug 21, 2015 4:11 pm
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But when I deleted all records from KSDS File, I was still able to browse the file
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Bill Woodger

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PostPosted: Fri Aug 21, 2015 4:25 pm
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Yes.... and?
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Robert Sample

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Joined: 06 Jun 2008
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PostPosted: Fri Aug 21, 2015 5:48 pm
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You need to find and read the Redbook VSAM Demystified where you can find all sorts of information about VSAM. The behavior you posted is normal and expected -- VSAM distinguishes between an empty file (that has never had a record) and a file with no records in it. They are not the same, so why would you expect the browse (or anything else, for that matter) to work the same?
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Jeenu Bajaj

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PostPosted: Fri Aug 21, 2015 7:01 pm
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Ok. Got it!! Thanks a ton guys for your answers!!
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Pete Wilson

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Joined: 31 Dec 2009
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PostPosted: Tue Sep 08, 2015 2:48 am
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Jeenu..once you load a record to a VSAM file it formats the Control Interval (or CI...kind of like a block in NONVSAM terms) and leaves it formatted even if you delete the record.

If no record is ever loaded to the file there are no formatted CI's and VSAM recognises the difference.

There's a program around on the web called VSAMINIT that will 'initialise' a file for you by inserting and (optionally) deleting a record into the file, but you could write your own version to.
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