Preventing structural damage to CDS and missing journal records

Perform the following steps to prevent structural damage to CDS and missing journal records:

1. Schedule reorganizations of CDSs to occur only when necessary. If the CDS is of adequate size, you should not have to reorganize often.
2. Use the proper procedures to reorganize your CDSs.
3. Ensure that no reorganization can occur when DFSMShsm is running on any MVS™ image in the complex. To do this:
   • Make sure that SYSDSN enqueues are in the system's inclusion list for global resource serialization (GRS); this allows the SYSDSN enqueues to be passed to all images in the complex that share the CDSs.
   • Modify the JCL used for reorganization of the CDSs by using a disposition of OLD whenever a DD statement refers to a CDS.
4. Define the DFSMShsm CDSs with VSAM SHAREOPTIONS(2 3).
5. Use the IDCAMS EXAMINE command to do preventive examines.
6. Reassess the number of backup versions you keep for the CDSs and journal. The more backup versions you have, the greater your chances are of having a good CDS and journal backup version to use should the need arise.

Related reading

• For more information about the procedures used to reorganize your control data sets, see the topic about reorganizing the control data sets in z/OS DFSMShsm Implementation and Customization Guide.
• For more information about defining VSAM SHAREOPTIONS for DFSMShsm, see the topic about VSAM SHAREOPTIONS for control data sets and the topic about control data set considerations in z/OS DFSMShsm Implementation and Customization Guide.