When starting an IMS region I am getting the message ACF0A202 INVALID REQUEST - UNDEFINED STORAGE TYPE and the ACF2/IMS interface does not initiate.
Verify that there is a GSO APPLDEF to define the IMS records. (Issue SHOW APPLDEF.) If there is an existing APPLDEF for the IMS records, then check the RSBLIB specified in the APPLDEF. Is the RSBLIB library valid, ie, is it defined, catalogued, populated, the correct release?
The RSBLIB should contain the following modules
ACFDC#EX
ACFDC#NE
ACFDC#OP
ACFDC#RE
ACFDC#SI
ACFDC#ST
ACFDC#SY
ACFDC#WT
Since there can be only one APPLDEF record for IMS, the RSBLIB must point to the highest release/version of ACF2 IMS (the IMS.CAX1IMS library).