A REG_NAMELIST request allows you to specify a list of data items for which you want to register interest. Each data item is represented by a registration block, mapped by the IXLYCRRB macro. The registration block contains information identifying the data item, its storage class, its vector index, whether to assign a directory entry, and whether the vector index is being reassigned to the current entry from some other entry in which interest will be deregistered. The registration blocks are contained in the storage area specified by BUFFER.

The system references the registration blocks by an index into the buffer and processes them sequentially beginning with the registration block identified by the first index (STARTINDEX) and ending with the data item identified by the last index (ENDINDEX).

The system returns state information for each processed data item represented by a registration block. The information is returned in the area specified by NSBAREA, and is mapped by the IXLYNSB macro.

A REG_NAMELIST request can complete prematurely because of a failure processing one of the registration blocks in the list or because the request exceeds the time-out criteria for the coupling facility. (Time-out criteria is model-dependent.) When a request completes prematurely, the system returns an index value (CAARNLINDEX) in the answer area which you can use to restart the REG_NAMELIST request.

A REG_NAMELIST request can be issued only for cache structures allocated in a coupling facility of CFLEVEL=2 or higher. REG_NAMELIST requests issued for a cache structure allocated in a coupling facility of CFLEVEL=0 or 1 will fail.