Implementing Siebel Business Applications on DB2 UDB for z/OS > Maintenance Considerations for z/OS > About Cursor Close >

Cursor Close Parameter Values on DB2 for z/OS

By default, on other DBMS platforms, Siebel Systems sets both DSMaxCursorSize and DSPreFetchSize to a value of -1, which causes the cursors to remain open to retrieve additional data.

When using DB2 for z/OS v7 and v8, setting the values of the DSMaxCursorSize and DSPreFetchSize parameters to -1 can cause a high number of DB2 Database Active Threads (DBAT); this can potentially lead to DB2 DBM1 address-space task abends (abnormal ends) caused by DBM1 virtual storage constraints. To alleviate this problem, Siebel Systems recommends that zSeries users set the MaxCursorSize and PreFetchSize parameters to positive values.

The minimum acceptable value that you can specify for the Cursor Close parameter is 32. The default value for both MaxCursorSize and PreFetchSize is 128. This value allows a reasonable number of rows to be retrieved without holding open the cursor. After the cursor is closed, the change is committed and the Database Active Thread (DBAT) becomes inactive.

Siebel Systems recommends that your corporate IT department and Siebel administrator collaborate to determine the values for these parameters that are most appropriate for each class of users connecting to DB2 for z/OS. The guidelines outlined above are not mandated, but they provide a balance between system resource utilization, user responsiveness, and productivity. However, your enterprise might have unique requirements beyond the scope of this chapter.