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Allocate Checkpoint Files

CA MIM checkpoint files are required if any one of the following is true:

• You intend to use the CTCONLY cross-system communication method. In this environment, the local checkpoint file on each system is used to store MIMplex system status information.
• You intend to use the XCF cross-system communication method. In this environment, the local checkpoint file on each system is used to store MIMplex system status information.
• You intend to use the Job Requeue feature of the ECMF. In this case, the local checkpoint file is used to track information associated with batch jobs that have been placed on hold (requeued) by ECMF.

Notes:

• If you are not sure whether to allocate checkpoint files at this point, then we suggest that you allocate them. The allocated checkpoint files can be deleted later if you decide not to use any of the CA MIM features that require CA MIM checkpoint files.
• CA MIM checkpoint files are not shared between CA MIM address spaces on different systems. You need at least one checkpoint file for each system in the MIMplex.
• CA MIM checkpoint files do not need to be allocated on shared DASD volumes.
• CA MIM serializes access to its checkpoint files by issuing ENQ SCOPE=SYSTEM requests; no hardware RESERVE requests are issued. CA MIM checkpoint files can be placed on DASD devices that have other data sets on them, provided that other applications do not have Hardware Reserve requests issued for the selected DASD unit.

Important: CA MIM does not support checkpoint files on the high portion of the Extended Address Volume (EAV). If you use EAV, make sure you allocate data sets with EATTR=NO.

To allocate checkpoint files

1. Customize and submit the job in the CAI.CBTDJCL(ALLOCKPT) member. This member also contains other helpful details.
2. Add CA MIM ALLOCATE commands to the CAI.CBTDPARM(MIMINIT) parmlib member.

   This ensures the new checkpoint files are allocated to the CA MIM address spaces during startup.

Notes:

• The usual naming convention for the CA MIM checkpoint files uses the system name as one of the data set name nodes.
• For more information about CA MIM checkpoint files and other cross-system communication methods, see the CA MIM Programming Guide.
• You may choose to allocate one or more checkpoint files for only one system in this step, and use CA MIM to deploy a copy to each system in the MIMPlex. For more information, see the CA MIM Programming Guide.