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DCBcb 'MODEL' IN JCL

 
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lindacline

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Joined: 25 Aug 2010
Posts: 3
Location: Michigan

PostPosted: Wed Aug 25, 2010 6:54 pm    Post subject: DCBcb 'MODEL' IN JCL
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Is there anything written anywhere concerning using DCB=(MODEL) in JCL (I can't find anything).
We are in the process of asking everyone to remove it because my understanding it is no longer needed. Documentation to pass along would be very helpful.

// DCB=(MODEL,RECFM=FB,LRECL=408)
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expat

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Joined: 14 Mar 2007
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PostPosted: Wed Aug 25, 2010 6:58 pm    Post subject:
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If your site is SMS mangaed and the ACs routines are correctly set up then yes, you are correct in saying that DCB=(MODEL is no longer required.

As for documentation to pass along ............... it was probably in the release notes about 20+ years ago when SMS was introduced icon_lol.gif
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lindacline

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PostPosted: Wed Aug 25, 2010 7:19 pm    Post subject:
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We are SMS managed.
Thanks for the info
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expat

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PostPosted: Wed Aug 25, 2010 7:27 pm    Post subject:
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Just so long as each and every dataset gets a DATACLAS allocated to it, everything will be fine. This also includes NON SMS and tape datasets.

I usually set up a DATACLAS called DEFAULT which has not attributes defined, and the ACS routines will allocate this DATACLAS if the filters do not allocate another.
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Anuj Dhawan

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PostPosted: Sun Aug 29, 2010 3:01 pm    Post subject:
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As Expat has mentioned, they are no longer required if DFsms is installed and tailored correctly. And, also, I've never tried to create a GDG-model ever at my shop.

However for the sake of theory -- long back, before you can create the files that attach to a GDG base, you need to create a model data-set that contains the DCB information for the files. This model data just needs to be a VTOC entry, it does not need to actually use up disk space. It is possible to create a different model dataset for every possible DCB combination, and some sites actually do that, but this needs a lot of effort to maintain. Many sites use a single model dataset, and then override the DCB information to build the correct type of file. To create a model DCB, use a dummy IEFBR14 job like this
Code:
//STEP2  EXEC PGM=IEFBR14
//MODEL1 DD   DSN=I.AM.GDG.MODEL,
//            DISP=(NEW,KEEP,DELETE),
//            UNIT=SYSDA,
//            SPACE(TRK,0),
//            DCB=(LRECL=80,RECFM=FB)
The SPACE=(TRK,0) parameter means that this file will just be created as a VTOC entry, it will not use up disk space.

Here is something which might also interest you, II08285: GDG GDS INFORMATION
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lindacline

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PostPosted: Tue Aug 31, 2010 12:47 am    Post subject: DCB=MODEL
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very helpful. Thanks
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Anuj Dhawan

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PostPosted: Tue Aug 31, 2010 1:32 am    Post subject:
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Glad to be helpful.
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