Shared-memory header
The shared-memory header contains a description of all other structures in shared memory, including internal tables and the buffer pool, and pointers to the locations of these structures.
When a virtual processor first attaches to shared memory, it reads address information in the shared-memory header for directions to all other structures.
The size of the shared-memory header is about 200 KB, but the size varies depending on the computer platform. You cannot tune the size of the header.