When writing a new data item to the cache structure, code WHENREG=NO to indicate that you do not have registered interest in the data item. Also, code WHENREG=NO if you want to update the cached copy of the data item regardless of whether you are currently registered. If the data item is new and you code WHENREG=NO, the system allocates cache structure resources when they are available, writes the data item to the cache structure, and registers your interest in the data item. If unused cache structure resources are unavailable, the system attempts to reclaim resources currently in use.

With a cache structure allocated in a coupling facility with CFLEVEL=5 or higher, you can optionally specify REGUSER to indicate whether the WRITE_DATA request should register interest in the entry. If you specify REGUSER=NO, keep in mind that the system gives preference to reclaiming those data items for which there is data but no registered interest.

With a cache structure allocated in a coupling facility with CFLEVEL= 9 or higher, code WHENREG=NO,ASSIGN=NO to specify that you do not want the system to write a data entry to the cache structure if the data item is new and an existing data entry is not found. The system does not create the data entry and returns IXLRSNCODENOENTRY to the user if the conditions are met. Coding or defaulting to WHENREG=NO,ASSIGN=YES for a new data item results in the system allocating cache structure resources when they are available, writing the data item to the cache structure, and registering your interest in the data item.

With a cache structure allocated in a coupling facility that supports write suppression based on local cache registration, code WHENREG=NO, ASSIGN=NO, LOCALREGCNTL=YES, CHANGED=YES to specify that you do not want the system to write changed data to the cache structure if the user requesting the write operation (local cache) is the only registered interest in the data item in the cache structure, and no subsystem data for the data item is cached. If conditions are met, the write request is suppressed, no data entry is written to the cache structure and the request completes with a reason code of IXLRSNCODELOCALREGWRTSUPPRESS.