Use the MSGROUTE statement to control the routing of subsystem modifiable messages (such as most MVS-issued messages). If you do not include a MSGROUTE statement, the routing attributes of the messages that originate from that processor are not modified by JES3 MSGROUTE processing. Even though MSGROUTE processing may not make modifications, a message is still eligible for other forms of JES3 message routing.

When a message is issued with multiple routing codes, JES3 selects a single routing code to use for MSGROUTE processing. See z/OS JES3 Initialization and Tuning Guide for more information.