RACF® requires that there be at least as many cache structure entries as there are local buffer slots for the associated data set. If this is not true, RACF remains connected to that structure but enters read-only mode. This will probably affect every system in the RACF data sharing group, but there might be exceptions if different systems use a different number of local buffers for the same data set. Regardless, there are several possible reasons for the cache structure being too small:

• The requested size for the RACF structure in the MVS™ policy is too small. In this case, IRRX011A is issued.
• The policy definitions specific to the RACF structures meet the minimum requirements, but the total of all the structures' policy definitions is greater than the amount of space available in the coupling facility. If the resulting size of a RACF structure still meets the RACF minimum, only message IRRX012I is issued, and the system can still enter data sharing mode. If not, IRRX012I and IRRX013A are issued and the system enters read-only mode as in the previous case.
• The policy's STRUCTURE statement specifies the INITSIZE keyword. The STRUCTURE statement should not specify INITSIZE, because RACF does not support the ALTER function of coupling facility structures. Specifying INITSIZE causes the size of the structure to be limited to the INITSIZE value instead of the SIZE value. If the INITSIZE value is less than the SIZE value, RACF issues an informational message, IRRX012I.

  IF RACF issues only message IRRX012I, the structure size (that is, the INITSIZE value) meets the RACF minimum, and the system can still enter data sharing mode. If IRRX012I is followed by message IRRX013A, the structure size is too small and the system enters read-only mode.

If the policy needs to be changed, the operator must decide whether to change RACF's mode across the sysplex while that change is being made. The choices are:

• Leave the system in read-only mode while the policy is being corrected, then issue the MVS SETXCF START,REBUILD operator command to rebuild the structures so that they reflect the new policy. See RACF support of the rebuild interface for more information.
• Issue RVARY NODATASHARE to put the sysplex into non–data sharing mode. This also causes RACF to disconnect from all structures. Because they are non-persistent, the structures are taken out of the coupling facility. Next update the policy and issue the SETXCF command to start the policy. After the policy has been started with the RACF-related modifications, issue the RVARY DATASHARE command; this causes RACF to reattempt connections so that the system can enter data sharing mode.