Use the Setcache Performance Entry panel to modify the caching characteristics of the storage control units. If you are using a Model 3990 Model 3 Storage Control, you have support for the caching of both read and write requests. If you are using a 3880-13 or 3880-23 Storage Control, you have support for the caching of read requests. In the terminology of the SETCACHE line operator, the caching of read requests is controlled by the READ CACHE or READ and SYSTEM CACHE functions. The caching of write requests is controlled by the DASD FAST WRITE, NON-VOLATILE STORAGE (NVS), and CACHE FAST WRITE functions.