General characteristics of messages and commands

Operators can issue commands to correct problems or to query the system to determine if it is operating properly. They often do this in response to system messages. Some messages require a reply from the operator. These messages are called WTORs (write-to-operator-with-reply). The operator responds to these messages by entering the REPLY command. Automation programs like NetView® use messages and command lists to simplify operator tasks and actions.

Messages and commands can be routed throughout a system or sysplex; the routing of messages and commands is an important part of operations planning. You want to ensure that operators are receiving the necessary messages at their consoles to perform their tasks. You want to be able to select the proper messages for suppression, automation, or other kinds of message processing.

Commands in a sysplex can run on other systems and affect system processing. In a sysplex, operators can also route commands from one system to another for processing. You might want to limit command processing to a specific system in the sysplex, or handle commands through command installation exits.

MVS™ messages have routing codes and message levels that, in large part, determine how messages are routed in a system or sysplex. Routing codes are decimal numbers from 1 to 128 that can be assigned to a console. Routing code functions include:

Indicating messages that require a specific operator action, such as routing code 1 (primary operator action).
Indicating messages that convey information about a specific system function or operator area. For example, messages with routing code 5 convey information about the tape library.
Indicating an error condition. For example, messages with routing code 10 convey information about a system error, an uncorrectable I/O error, or information about system maintenance.
Indicating a more specific meaning. For complete information, see any volume of z/OS® MVS System Messages.

For MCS, SMCS and extended MCS consoles, you can specify which routing codes the console is to receive.

Message levels allow MVS to select messages according to the severity of the condition or situation described in the message. Message levels can range from WTOR messages that require an operator response, to informational messages that indicate system status. You assign these levels to specific MCS, SMCS or extended MCS consoles so the system can direct messages at those levels to the console. For example, you can assign message level (R) for WTOR messages to a full-capability console that handles critical system messages. Assigning message levels to the appropriate consoles in your configuration is a good way to control message traffic for MCS, SMCS and extended MCS consoles.

The system sometimes issues synchronous messages that bypass normal message delivery. These messages might require immediate operator action or can indicate system problems. You can define a group of consoles from which MVS can select a candidate to display these synchronous messages. For more information, see Defining console configuration.