You should periodically remove old information from the DBC.Acctg table. For example, the following command will delete entries for September 2006:
DELETE FROM DBC.ACCTG WHERE SUBSTR(ACCOUNTNAME, 1, 6) = 'CB0609';
To minimize performance impact, perform any necessary maintenance to DBC tables when the system is quiescent or least busy. Cleaning certain tables, such as DBC.AccLogTbl lock the table and prevent access to the system.