Introduction

Multiple virtual storage (MVS™) uses the Job Entry Subsystem 3 (JES3) portion of MVS/System Product - JES3 to control the input, processing, and output of jobs. JES3 services the job processing requirements of one to 32 physically connected MVS processors called mains. Viewed as a whole, the one- to 32-main environment serviced by JES3 is called a complex.

JES3 has its own private address space in each of the mains in the complex. One main, the JES3 global main, is in control of the entire complex. There must be a global main; if there is only one main in the complex, that main is the global. In a complex with more than one main, the other mains in which JES3 resides are called local mains. There can be as many as 31 local mains. JES3 is designed so that if the global fails, any properly-configured local within the complex can assume the function of the global through a process called dynamic system interchange (DSI). Figure 1 illustrates the basic structure of a JES3 complex.

You control MVS and JES3 through the operator's console. You can use a display console, such as the IBM® 32xx series as an operator's console.

You use commands to control the processors and system resources. This topic describes the commands you use to control the JES3 portion of the operating system. For a complete description of MVS commands, see z/OS MVS System Commands.

JES3 displays messages to the operator console in response to either system activity or in response to an operator command such as an *INQUIRY or *MODIFY request.