MVS - Multiple Virtual Storage, is an operating system from IBM that runs on system/370 and system/390 IBM mainframe computers.
TSO - Time Sharing Option, lets remote terminal users invoke MVS facilities interactively.
ISPF - Interactive System Productivity Facility, runs a part of TSO and utilizes full screen capability of 3270 terminals.
PDF - Program Development Facility, part of the ISPF.
RACF - Resource Access Control Facility, identifies both users and resources.
SMF - System Management Facility, facilitates billing and monitoring.
Ex. CPU time used, amount of DASD etc..
SMS - Storage Management Subsystem, automates data management services of MVS.
JES - Job Entry Subsystem, provides job management facilities on MVS.
DASD - Direct Access Storage Device
