Abstract: Initialization time of a peripheral storage subsystem is reduced. Each subsystem includes a cache store plus a back store having a plurality of DASD storage devides. Storage locations in the cache store are initially allocated for an index table for other subsystem control structures, track buffers, and a limited number of data storing record slots. Limiting the allocation of record slots reduces initialization time. The number of record slots initially allocated is determined by a maximum allowable system initialization time, a total number of subsystem devices to be initialized and the time required to initialize each record slot.