Changes required to use VSAM as a CMT and UMT

Rohit Umarjikar · Posted: Tue Aug 27, 2013 2:20 pm

Team,

I would like to know if a KSDS is needs to be used as a UMT/CMT then where all we need to make the changes as far as system parameters are concerned ?

Bill O'Boyle · Posted: Wed Aug 28, 2013 2:05 am

Check the necessary parameters via the RDO/CEDA FILE definition, which are normally defined by your CICS Sysprog and/or Tech Services personnel.

Review the associated "CICS System Definition Guide" for your current CICS version/release for further explanation.

colin777 · New User Joined: 06 Jun 2013 Posts: 19 Location: Singapore

Hi,

In addition to Bill's comments, make sure the application can support the Data Table.

For a User Maintained Data Table (UMT), the full File Control API commands are not available. For a CICS startup, it opens the UMT VSAM file, reads all the records into a Data Space and then closes it. This file can be taken to other systems that might also want access. This type of approach really suits an ESDS structure that is needed for Read-Only.

For a CICS Maintained Data Table (CMT), all the File Control commands are available, as in Delete, Update and Write. This means that CICS will keep all changes made to the Data Table in sync with the source dataset.

If the CMT is needed by multiple AORs, then consider a Shared Data Table for your CMT, this is much faster than using a File Owning Region and the mirror task.

CICS will allocate the size of the Data Space based on the MAXNUMRECS option in the File Control entry. Be careful if you take the NOLIMIT default option, as it could affect your Paging subsystem.

HTH

Colin777

Rohit Umarjikar · Posted: Thu Aug 29, 2013 12:08 pm

Thank you Bill and Colin for the useful information.