Host Software Component (HSC) library management software enables StorageTek's automated tape libraries to operate in an MVS environment. The software manages the interface between the operating system and each automated cartridge system for MVS and VM tape environments. In the process, HSC software delivers the benefits of centralized storage management to mainframe environments.
HSC software acts as the host interface in MVS and VM tape environments. It is designed to work in tandem with other tape management software.
HSC software allows supported applications to dynamically allocate library resources without hard-partitioning tape slots.
You could get more information at Storagetek on the Web.