It is strongly recommended that you name the system console in CONSOLxx. You can specify a name for the system console using the NAME keyword. Select a unique name for the system console that cannot be confused with a valid device number. (For other console naming restrictions, see Restrictions for console names.)
If your operator specifies CON=NONE, or if you do not name the system console in CONSOLxx, MVS™ tries to use the name of the system to which the console is attached as the name of the system console. The system uses the system name defined on the IEASYSxx parameter SYSNAME as long as that name is unique and cannot be interpreted as a valid device number. If you do not name the system console in CONSOLxx, use a system name that cannot be confused with a device number that the system can use. For example, do not use a system console name like ABC, BAD, or C01.
If you specify a system name that the system can interpret as a valid device number, the system does not use SYSNAME as the name of the system console. If the system cannot use SYSNAME for the system console name, or if the system console name is not unique, the name of the system console is SYSCNxxx, where xxx is a three-character suffix generated by the system.