By default, DB2 ODBC connection pooling is on with timeout = 60 sec. That is, a connection will be removed from the pool if the connection is not used for 60 sec. There is no max/min bound for ODBC connection pool; it is unbounded. OLEDB resource pooling for MSDASQL is also on. That means that connection could be pooled on both at OLEDB level and at ODBC level. The behavior of OLEDB resource pool is different to ODBC. It does not have max/min bound either. However, OLEDB will drop the entire pool when there are no active connections. In order to keep the pool, Microsoft suggests having code to keep one connection open (see http://msdn2.microsoft.com/en-us/library/ms810829.aspx).

IBM suggests that we disable OLEDB resource pooling for MSDASQL (see http://publib.boulder.ibm.com/infocenter/db2luw/v8/index.jsp?topic=/com.ibm.db2.udb.doc/ad/c0010958.htm) so that it does not interfere with ODBC resource pooling. By default, both OLEDB resource pooling and ODBC connection pooling on.