VSAM Tips.
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All of these Tips/Tuning-suggestions should be tested your own, at your shop, prior to use in Prod.
All of these Tips/Tuning-suggestions should be tested your own, at your shop, prior to use in Prod.
- Anuj Dhawan
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VSAM Tips.
1. CICS, DB2, IMS can process records in existing VSAM data-sets but can't create the data-set. Even you can process VSAM data sets in COBOL programs only after you create them with access method services.
Thanks,
Anuj
Disclaimer: My comments on this website are my own and do not represent the opinions or suggestions of any other person or business entity, in any way.
Anuj
Disclaimer: My comments on this website are my own and do not represent the opinions or suggestions of any other person or business entity, in any way.
- Anuj Dhawan
- Founder
- Posts: 2805
- Joined: Sun Apr 21, 2013 7:40 pm
- Location: Mumbai, India
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Re: VSAM Tips.
2. To specify dummy VSAM dataset in a JCL, Code AMP=’AMORG’ . This parameter tells the OS to treat the file as VSAM file. E.g.:
Code: Select all
//NOVSAMIO DD DUMMY,AMP=’AMORG’
Thanks,
Anuj
Disclaimer: My comments on this website are my own and do not represent the opinions or suggestions of any other person or business entity, in any way.
Anuj
Disclaimer: My comments on this website are my own and do not represent the opinions or suggestions of any other person or business entity, in any way.
- Anuj Dhawan
- Founder
- Posts: 2805
- Joined: Sun Apr 21, 2013 7:40 pm
- Location: Mumbai, India
- Contact:
Re: VSAM Tips.
3. If you want to make VSAM-data-set read-only, use INHIBIT along with ALTER command:
Notice that the ALTER command is used with DATA and INDEX and not with the cluster.
Code: Select all
//STEP1 EXEC PGM=IDCAMS
//SYSPRINT DD SYSOUT=*
//SYSIN DD *
ALTER -
SECRET.KSDS.DATA -
INHIBIT
ALTER -
SECRET.KSDS.INDEX -
INHIBIT
/*
//*
Thanks,
Anuj
Disclaimer: My comments on this website are my own and do not represent the opinions or suggestions of any other person or business entity, in any way.
Anuj
Disclaimer: My comments on this website are my own and do not represent the opinions or suggestions of any other person or business entity, in any way.
- Anuj Dhawan
- Founder
- Posts: 2805
- Joined: Sun Apr 21, 2013 7:40 pm
- Location: Mumbai, India
- Contact:
Re: VSAM Tips.
4. A VSAM data-set created with REUSE can be treated as a new data-set at any subsequent time. In a way, you can say that VSAM equivalent of temp data-set is to create VSAM file with REUSE option.
Thanks,
Anuj
Disclaimer: My comments on this website are my own and do not represent the opinions or suggestions of any other person or business entity, in any way.
Anuj
Disclaimer: My comments on this website are my own and do not represent the opinions or suggestions of any other person or business entity, in any way.
- Anuj Dhawan
- Founder
- Posts: 2805
- Joined: Sun Apr 21, 2013 7:40 pm
- Location: Mumbai, India
- Contact:
Re: VSAM Tips.
5. IDCAMS Utility can't be executed without the SYSPRINT and SYSIN DD names.
Thanks,
Anuj
Disclaimer: My comments on this website are my own and do not represent the opinions or suggestions of any other person or business entity, in any way.
Anuj
Disclaimer: My comments on this website are my own and do not represent the opinions or suggestions of any other person or business entity, in any way.
- Anuj Dhawan
- Founder
- Posts: 2805
- Joined: Sun Apr 21, 2013 7:40 pm
- Location: Mumbai, India
- Contact:
Re: VSAM Tips.
Thanks for the feedback Neeraj - glad, you find them helpful.
Regards,
Regards,
Thanks,
Anuj
Disclaimer: My comments on this website are my own and do not represent the opinions or suggestions of any other person or business entity, in any way.
Anuj
Disclaimer: My comments on this website are my own and do not represent the opinions or suggestions of any other person or business entity, in any way.
-
- Registered Member
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- Location: India
- Anuj Dhawan
- Founder
- Posts: 2805
- Joined: Sun Apr 21, 2013 7:40 pm
- Location: Mumbai, India
- Contact:
Re: VSAM Tips.
Great - nice to know that!
Regards,
Regards,
Thanks,
Anuj
Disclaimer: My comments on this website are my own and do not represent the opinions or suggestions of any other person or business entity, in any way.
Anuj
Disclaimer: My comments on this website are my own and do not represent the opinions or suggestions of any other person or business entity, in any way.
- Anuj Dhawan
- Founder
- Posts: 2805
- Joined: Sun Apr 21, 2013 7:40 pm
- Location: Mumbai, India
- Contact:
Re: VSAM Tips.
6. Advice: One should remove Catalog Orphans from the Catalog, (if you're in the capacity of doing it).
Thanks,
Anuj
Disclaimer: My comments on this website are my own and do not represent the opinions or suggestions of any other person or business entity, in any way.
Anuj
Disclaimer: My comments on this website are my own and do not represent the opinions or suggestions of any other person or business entity, in any way.
- Anuj Dhawan
- Founder
- Posts: 2805
- Joined: Sun Apr 21, 2013 7:40 pm
- Location: Mumbai, India
- Contact:
Re: VSAM Tips.
7. As an Application Developer (assuming COBOL as the Application language) - for sequential access of VSAM, request more data buffers. For random access, request more index buffers.
One should specify both BUFND and BUFNI when ACCESS IS DYNAMIC.
Avoid coding additional buffers unless your application will run interactively; then code buffers only when response-time problems arise that might be caused by delays in input and output.
One should specify both BUFND and BUFNI when ACCESS IS DYNAMIC.
Avoid coding additional buffers unless your application will run interactively; then code buffers only when response-time problems arise that might be caused by delays in input and output.
Thanks,
Anuj
Disclaimer: My comments on this website are my own and do not represent the opinions or suggestions of any other person or business entity, in any way.
Anuj
Disclaimer: My comments on this website are my own and do not represent the opinions or suggestions of any other person or business entity, in any way.
- Anuj Dhawan
- Founder
- Posts: 2805
- Joined: Sun Apr 21, 2013 7:40 pm
- Location: Mumbai, India
- Contact:
Re: VSAM Tips.
8. As a COBOL Application Developer, if you can choose this -for 'best performance', access records sequentially.
Dynamic access is less efficient than sequential access, but more efficient than random access. Random access results in increased EXCPs because VSAM must access the index for each request.
Dynamic access is less efficient than sequential access, but more efficient than random access. Random access results in increased EXCPs because VSAM must access the index for each request.
Thanks,
Anuj
Disclaimer: My comments on this website are my own and do not represent the opinions or suggestions of any other person or business entity, in any way.
Anuj
Disclaimer: My comments on this website are my own and do not represent the opinions or suggestions of any other person or business entity, in any way.
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