Mandatory for GETMAIN SHARED, it indicates the IPCKEY of the shared memory segment used for GETMAIN SHARED.

The IPCKEY must be unique for shared memory. If the IPCKEY value specified to KIX_SHR_IPCKEY is in use, then the feature does not work correctly -- if the shared memory with this IPCKEY is not used for GETMAIN SHARED, then server failed to boot; if it is used for GETMAIN SHARED, then server tries to attach to the shared memory and tries to use it to allocate memory.