In case you need to change the CCI SYSID, please find here the recommended way to do this.
The CCI SYSID is defined in the CCIPARMS statement SYSID in ENF. Once you have changed this parameter an IPL is required to activate the change.
Do NOT change the SYSID in CCI by updating the CCIPARMS and restarting ENF, or BY issuing the SYSID command from the console. The results of this would be unpredictable.