This parameter determines the memory size used by the cluster caching facility, also known as CF, for group buffer pool (GBP) usage for this database.
There are two main types of resources in the GBP, directory entries and data elements. A directory entry stores metadata information pertaining to a page. A data element stores the actual page data.
DB2 members continue to cache pages in their own local buffer pools. The GBP is used only by the local buffer managers to maintain intersystem buffer coherency and cannot be directly referenced by DB2 EDUs running on any DB2 member.