Problem:

Can the Microfocus Mainframe Access product support the z/OS environment that has the following parm specified in the DIAGxx parmlib member: VSM ALLOWUSERKEYCSA(NO)

Resolution:

This will normally default to NO on zOS 1.9 (our version at CSIMVS DOES NOT SPECIFY IT - so it is OFF).

It looks like some software vendors would require it (notably ADABAS from Software AG, Datacom from CA)

The implication is that performance may be improved for very-large databases.  And some software vendors exploit it.  MFA does not.    Other DBMS systems use data spaces rather than CSA. (aka shared memory)