As part of the process of managing cache structure resources, you can provide a reclaim vector that overrides the default resource reclaim algorithm. The reclaim vector applies to the storage class that you specify. You can override the default algorithm by providing a reclaim vector for some or all of the storage classes, or use the default algorithm for all storage classes.

When you write a new data item to the cache structure, or read a data item that is undefined in the cache, the system must allocate cache structure resources for that data item. By default, when you have not defined a reclaim vector and unused storage resources are not available, the system attempts to reclaim the least recently used resources that belong to data items in the storage class specified on the request. If those resources are unavailable from the storage class specified on the request, and you have not provided a reclaim vector, the system fails the request. However, if you have provided a reclaim vector for the storage class, the system uses the vector specifications to try to obtain resources from other storage classes to satisfy the request.