Reorganizing RECON Data Sets


Because all current levels of VSAM support CI reclaim (and DBRC does not turn CI reclaim off), the requirement to reorganize RECON data sets to reclaim space is diminished. For instance, when all the records in a CI are erased, the CI is returned to the free CI pool in the CA. Some users reorganize their RECON data sets on a monthly basis.

A plan for reorganizing the RECON data sets to reclaim this space on a regular basis must be considered. The RECON data sets can be reorganized while the IMS online systems are active.

The RECON data sets can be reorganized easily and quickly with the use of a few DBRC and AMS commands. The AMS REPRO command copies one RECON data set to another, reorganizing it during the process. This command, combined with a DELETE and a DEFINE of the RECON data sets, is enough to complete a reorganization.

Additional information to consider when designing the RECON data set reorganization procedures, related to the IMS TM status, are as follows:

  • If the online system is active, a reorganization of the RECON data sets should be scheduled:

    - During a period of low RECON data set activity.

    - When no batch, DL/I, or DBB jobs or utilities are running.

    Each online system that uses the RECON data sets must issue a LIST.RECON STATUS command after the CHANGE.RECON REPLACE command is issued, in order to deallocate the RECON data set before deleting and redefining it.

  • If the online system is not active, a reorganization of the RECON data sets should be scheduled:

    - After the RECON has been backed up (using the BACKUP.RECON command).

    - When no subsystems are allocating the RECON data sets.



Introduction to IMS. Your Complete Guide to IBM's Information Management System
An Introduction to IMS: Your Complete Guide to IBMs Information Management System
ISBN: 0131856715
EAN: 2147483647
Year: 2003
Pages: 226

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