The LLA/VLF enables the storage of load module directories as well as the load modules themselves. LLA/VLF control is specified at a library level. With the inclusion of the BMF/Hiperspace Cache, extra care should be maintained to avoid unnecessary slow-downs. Any program object that is cached in Hiperspace and LLA/VLF concurrently will eventually be dropped from the Hiperspace Cache due to inactivity. For this reason, it is better to prevent these program objects from going into the Hiperspace in the first place.
BMF/Hiperspace Caching closely parallels LLA/VLF in concept; both are used to offset the cost of I/O processing, and both have a maximum capacity of 2GB. Hiperspace Caching is dynamic, utilizing the LRU to purge member pages so that recent or more frequently used member pages are accessible without I/O operations. Since the LRU is constantly checking the status of member pages in the Hiperspace, CPU utilization is increased, though I/O processing is decreased. Striking a balance between these two factors is key to employing the Hiperspace efficiently and effectively.
VLF outperforms Hiperspace caching for program objects, however, VLF does not cache program objects with Multiple Segments (RMODE=SPLIT), whereas all formsof PDSE data members and program objects can be cached in the Hiperspace.
