Configuration considerations for XA transaction managers

You should consider the following configuration parameters when you are setting up your TP monitor environment: tp_mon_name, tm_database, maxappls, and autorestart.

• tp_mon_name

  This database manager configuration parameter identifies the name of the TP monitor product being used (for example, TXSeries® CICS®).

• tm_database

  Because Db2® does not coordinate transactions in the XA environment, this database manager configuration parameter is not used for XA-coordinated transactions.

• maxappls

  This database configuration parameter specifies the maximum number of active applications allowed. The value of this parameter must be equal to or greater than the sum of the connected applications, plus the number of these applications that may be concurrently in the process of completing a two-phase commit or rollback. This sum should then be increased by the anticipated number of indoubt transactions that might exist at any one time.

  For a TP monitor environment (for example, TXSeries CICS), you may need to increase the value of the maxappls parameter. This would help to ensure that all TP monitor processes can be accommodated.

• autorestart

  This database configuration parameter specifies whether the RESTART DATABASE routine will be invoked automatically when needed. The default value is YES (that is, enabled).

  A database containing indoubt transactions requires a restart database operation to start up. If autorestart is not enabled when the last connection to the database is dropped, the next connection will fail and require an explicit RESTART DATABASE invocation. This condition will exist until the indoubt transactions have been removed, either by the transaction manager's resync operation, or through a heuristic operation initiated by the administrator. When the RESTART DATABASE command is issued, a message is returned if there are any indoubt transactions in the database. The administrator can then use the LIST INDOUBT TRANSACTIONS command and other command line processor commands to find get information about those indoubt transactions.