Resizing the inactive ACB library online

Occasionally, the size of the ACB library needs to be adjusted. The methods of bringing the change online differ depending on how the data set is allocated; with JCL or dynamically using the DFSMDA macro.

When JCL is used for allocation, IMS must be brought down and restarted to recognize the changes. To avoid having to take IMS down to perform this task, use dynamic allocation for both the active and inactive ACBLIB data sets and then perform an online change process to bring the resized ACB libraries online.

Example

Due to rapid application development cycle, an ACB library might need to be enlarged frequently. If both the active and inactive ACB libraries are dynamically allocated using the DFSMDA macro, resizing of the ACBLIBs will not require an IMS outage.