Per the z/OS Enhancements in the 14.2 documentation set:
MVSMON Parmlib Member Statement Removed
The MONITOR statement for CPU has been removed. CPU logical processors (thread) and cores are always monitored. There is no longer a need to specify the processor IDs to be monitored. The MONITOR definition for the metric CPU is now obsolete.
If a MONITOR statement for CPU is currently specified in the parmlib member MVSMON, it should be removed. If not removed, an error is generated during initialization.
If the MVS data collector is being warm started, the MVS monitor definitions are obtained from the CA SYSVIEW persistent data store.
The first time that CA SYSVIEW is started, the prior monitor definitions are processed. If a MONITOR CPU statement is present, an error is generated. The data collector automatically removes the obsolete MONITOR statement when the data is saved in the persistent data store.