DFSMS: Data Facility Storage Management Subsystem
DFSMSdfp: Data Facility Product
DFSMSdss: Data Set Services
DFSMSrmm: Removable Media Manager
DFSMShsm: Hierarchical Storage Manager
DFSMStvs: Transactional VSAM Services
DFSMSopt: Optimizer
See ABCs of z/OS System Programming Volume 3 (SG24-6983), https://www.redbooks.ibm.com/redbooks/pdfs/sg246983.pdf.