Each database in a DB2 instance is associated with a heap (temporary storage) but the default size of the heap (measured in 4 KB pages) is too low for the broker to use. Therefore, if you create broker databases in DB2, you must increase the value of the Database Heap Size parameter for each broker database to ensure that the heap size is at least 900, which gives the broker database 3600 KB of storage space (that is, 900 multiplied by 4 KB pages).