Modifying IMS system data sets using online change
You can modify the IMS system data sets MODBLKS, MATRIX, and ACBLIB using online change.
About this task
Each of IMS system data sets must be present
in the following copies:
- A staging library, which is identified by an unsuffixed DD statement (MODBLKS, MATRIX, ACBLIB), and is used offline only to prepare changes to the active library.
- An active and an inactive library, which are used in flip-flop mode and are identified by suffixed DD statements (MODBLKSA and MODBLKSB, and so on). The same parameter (MODBLKSx, where x= A or B) controls the active library for both MODBLKS and MATRIX. While the active library (either ...A or ...B) is being used online by DBCTL, you can use the online change utility to copy the contents of the staging library to the inactive library. You use a series of /MODIFY commands to perform the actual switch from the active library to the updated inactive library.
The IMS.MODSTAT data set, which is created during the IMS system generation and updated automatically, indicates which of the suffixed data sets is currently active. For guidance on using online change, see Changing DBCTL resources online and IMS: System administration.