There is no IPL requirement to load a new LMP key. After updating the appropriate "KEYS" member that is referenced by the CAS9 procedure (executes PGM=CAIRIM), issue command "S CAS9...LMPKEYS" to allow CAS9 to run and read only the KEYS.
Other Relevant Information
Passing the LMPKEYS option on the START command directs CAIRIM to read only the //KEYS DD statement. This procedure will prevent the //PARMLIB DD from being read and thus the statements contained within from being processed. Furthermore, only the initial execution of CAS9 will read the //AUTOCMDS DD statement. Any desire to process the AUTOCMDS will require a special START command. Further information can be found in the CA Common Services Administrator Guide.