The SYSIDNT system initialization parameter specifies a 1- to 4-character name that is known only to your CICS® region.
The value for SYSIDNT, whether specified in the SIT or as an override, can only be updated on a cold start. After a warm start or emergency restart, the value of SYSIDNT is that specified in the last cold start.
For information about the SYSIDNT of a local CICS region, see The local CICS region name.