Glossary of IBM MVS System Acronyms and Terms

CICS	Customer Information and Control System - Online transaction processor that runs under MVS, handles user-written transaction processing application programs
CLIST	Command List - Set of command interpreted by MVS JCL processor and TSO
HLQ	High Level Qualifier - 1st part of a data set name or library name, used to identify its creator or owner
ISPF	Interactive Structured Programming Facility - Application that runs under TSO and allows access to library members and data sets
JCL	Job Control Language - Control statements to direct the operating system when processing a batch job
JES	Job Entry Subsystem - Controls input and output to MVS Jobs are read by JES, output is viewed or routed by JES
LLQ	Low Level Qualifier - last part of a data set name or a library name, used to identify its type
MVS or OS/390	Multiple Virtual Systems or Operating System/390 - the operating system
PDS and PDSE	Partitioned Data Set Extended - libraries
RACF	Resource Allocation and Control Facility - security product
SMS	System Managed Storage - component of the operating system that handles placement of data sets on DASD devices
TSO	Time Sharing Online - Online Interface to MVS System and system products