The routing codes are specified in the ROUTCDE parameter of the WTO or WTOR macro. If you specify a message which contains no routing codes, MVS™ may provide one or more default routing codes, based upon the presence or lack of other queuing specifications.
If you specify a message containing descriptor codes but no routing codes and no target console, MVS will not assign any routing codes and will write the message to the hardcopy log.
If you specify a message containing no routing codes, no descriptor codes, and no target console, MVS will assign a default set of routing codes. This set of default routing codes is specified at MVS initialization on the DEFAULT statement in your CONSOLxx parmlib member. If a set of default routing codes was not provided on the DEFAULT statement, MVS will assign routing codes 1 through 16.