Allowing the system to page-fix storage (PAGEABLE=YES) is faster than using the PGSER services. However, specifying PAGEABLE=YES results in slower IXLCACHE performance than specifying PAGEABLE=NO because it takes more time for IXLCACHE to ensure that the virtual storage is backed by central storage. Additionally, if you issue IXLCACHE multiple times and reuse the same storage areas to pass information, you might obtain better performance if you issue a single PGSER invocation and specify PAGEABLE=NO than if you specify PAGEABLE=YES and allow the system to fix storage on each IXLCACHE invocation.

When selecting an option, consider how many requests you will issue and whether you plan to use the same storage buffers on multiple requests. For example, if you plan to write changes from the buffer to permanent storage as part of the store-through cache method, and must page-fix the storage yourself for such a write, specifying PAGEABLE=YES on the read request for the data in the cache structure has no effect on the page fixing for the write to permanent storage. In such a scenario, because you must provide the page fixing for the write to permanent storage anyway, for improved performance, you might specify PAGEABLE=NO on the IXLCACHE request and page-fix the storage yourself when you write the data from local buffers to the cache structure.

See Using Real Versus Virtual Storage for more information about specifying pageable and nonpageable virtual storage.