Based on the comments inside PSQ20RCB from the SAMPJCL member:
RECEIVE SYSMODS FROMNTS(PSQ6B0)
SELECT (
CAX4260 /*CA-PANSQL COMMON-MVS COMPONENTS */
CB2A260 /*CA-PANSQL FOR Db2 */
/*CB2A261 /*CA-PANSQL FOR Db2 CICS */
/*CC55260 /*CA-PANSQL CICS COMMON MODULES */
CC56260 /*CA-PANSQL Db2 IDMS AND DATACOM COMMON MODULES */
/*CB2D260 /*CA-PANSQL FOR DATACOM */
/*CB2D261 /*CA-PANSQL FOR DATACOM CICS */
/*CB2E260 /*CA-PANSQL FOR IDMS */
/*CB2E261 /*CA-PANSQL FOR IDMS CICS */
/*CB2B260 /*CA-PANSQL FOR ORACLE */
) .
Both CAX4260 and CB2A260 are needed.
You should only need CC56260 if you have IDMS and/or DATACOM and are running Easytrieve programs with either of these.
However, both CAX4260 and CC56260 are prerequisites for CB2A260.
So, at a minimum the above three are needing to be selected for the PSQ20RCB member to run successfully.