MAX USERS field (CTHREAD subsystem parameter)
The CTHREAD subsystem parameter controls the maximum number of allied threads that are to be allocated concurrently. Allied threads are threads that are started at the local subsystem.
| Acceptable values: | 1 - 20000 |
|---|---|
| Default: | 200 |
| Update: | option 19 on panel DSNTIPB |
| DSNZPxxx: | DSN6SYSP CTHREAD |
Count each of the following items as separate users:
- Each TSO user (whether running a DSN command or a Db2 request from QMF)
- Each batch job (whether running a DSN command or a Db2 utility)
- Each IMS region that can access Db2
- Each active CICS® transaction that can access Db2
- Each utility (each utility uses one thread, plus one thread for each subtask)
- Each connection from users of CAF and RRSAF
- Each WebSphere application server or other application server that uses JDBC or ODBC has multiple connections to DB2. The number of connections is determined by the application server.
The maximum number of threads accessing data that can be allocated concurrently is the sum of the value of the MAX USERS field and the MAX REMOTE ACTIVE field on panel DSNTIPE. The maximum allowable value for this sum is 20000. When the number of users who are attempting to access Db2 exceeds the number that you specify, excess plan allocation requests are queued. In most situations, the amount of real storage determines the maximum number of threads that Db2 can handle.
Due to parallelism, Db2 utilities each use a minimum of one thread, plus an additional thread for each subtask. Therefore, a single utility might use many threads. Specify a thread value accordingly to accommodate parallelism within utilities. Consider using a value that is higher than the default value or the value that you specified in a previous version of Db2.