JES2 allows two or more members of a multi-access spool (MAS) configuration to share commands while retaining unique values in those commands. A single command can affect multiple, unique entities on different JES2 members, allowing you to view a MAS as a single image with one point of control.

System symbols represent unique values in shared commands. Each member defines its own values to system symbols. When shared commands are processed, each member replaces the system symbols with its own values.

Before you use system symbols in JES2 commands, you must understand the types of system symbols, the elements that comprise them, and the general rules for using them. See z/OS MVS Initialization and Tuning Reference, SA23-1380for details about planning to use system symbols.