With the store-through cache method, you write to permanent storage and to the cache structure at the same time and with the same serialization. Thus, you do not need to obtain the cast-out lock to serialize the update to permanent storage.

For recovery in a multisystem environment, you can optionally obtain the lock through the IXLCACHE REQUEST=WRITE_DATA with the GETCOLOCK=YES option. If the system that performs the cast out obtains the lock and fails, users on other systems can recognize that data items locked by the user might not be valid as a result of the failure.

When you write the changes to the cache structure, you request that the system invalidate the copies of the data item for other users. To write the data item to permanent storage, use the access method that you usually use to access permanent storage. After completing the write operation, use IXLCACHE REQUEST=UNLCOCK_CASTOUT or REQUEST=UNLOCK_CO_NAME to free the cast-out lock. You can use the UNLOCK_CASTOUT request once to free multiple locks at the same time you can issue the UNLOCK_CASTOUT request once to free a single lock. The UNLOCK_CO_NAME request allows you to free only a single lock, and is a more efficient method than UNLOCK_CASTOUT for releasing a single lock.