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cobcurious
Beginner
Joined: 04 Oct 2003
Posts: 68
Topics: 25
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 Posted: Thu Dec 18, 2003 7:14 am Post subject: GDG related doubt |
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Hi,
Can anybody please tell me whats is the structure of a base GDG ? I have tried making different versions of different LREC manually by copying and changing the "Gnnn" of a prev generation.It works!! Why is it not possible to make a VSAM file as one of the generations of a GDG?
Regards
cobcurious |
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SureshKumar
Intermediate
Joined: 23 Jan 2003
Posts: 211
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| Posted: Thu Dec 18, 2003 9:00 am Post subject: |
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Cobcurious,
Simple answer is - GDG is for a Flat File system. As you have tested LRECL does not matter but VSAM is a sophisticated file management system. If you would have noticed we do not create a VSAM file in a job step, its done externally thru IDCAMS and they have different flavors (KSDS,ESDS..) and a different storage management system than GDG's which is managed by SMS. |
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Mike Chantrey
Intermediate
Joined: 10 Sep 2003
Posts: 234
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Location: Wansford
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| Posted: Thu Dec 18, 2003 9:28 am Post subject: |
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Suresh said: | Quote: | | we do not create a VSAM file in a job step |
This is not correct; with SMS active you can create VSAM files in any job step.
It's not as flexible as creating them with IDCAMS however. For example see an up-to-date version of the JCL reference and look up the RECORG subparameter of the DD statement. This allows you to specify the type of VSAM file you are creating.
However, you still can't use them with GDGs and probably never will be able to. There's ultimately no technical reason why IBM couldn't create some sort of VSAM GDG-like feature but they won't because that's just not what VSAM and GDGs are for. The closest you can probably get is using IDCAMS or similar method to dump VSAM files into flat files in a GDG. |
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cobcurious
Beginner
Joined: 04 Oct 2003
Posts: 68
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| Posted: Sun Dec 21, 2003 10:53 pm Post subject: |
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Hi,
Thank you Suresh Kumar and Mike Chantrey for your replies.But I have not got the answer for | Quote: |
whats is the structure of a base GDG ?
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I request anyone to explain as to what does the base GDG contain ? Does it contains the name of the associated generations ?
Pls let me know
Regrds
Cobcurious |
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kolusu
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Joined: 26 Nov 2002
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Location: San Jose
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