SIZE= parameter on EXEC IDMSDC startup JCL for VSE

We are Upgrading IDMS from 16.0 to 18.5 for zVSE 5.2, what are the requirements for SIZE= parameter on EXEC IDMSDC startup JCL?

The majority of the IDMS CV is built in GETVIS storage.

SIZE= on the EXEC IDMSDC startup JCVL statement should be as small as possible.

As of the 18.5 release, It must be at least large enough to contain the IDMSDC startup module plus modules RHDCOPTS, WTOEXIT, WTOREXIT and RHDCFTAB

https://docops.ca.com/ca-idms/19/en/administrating/administrating-ca-idms-system-operations/sample-z-vse-jcl#Samplez/VSEJCL-z/VSEDC/UCFStartupJCL