set_thread_count
Declares an approximate number of threads in the database environment.
The syntax of the entry in in the DB_CONFIG file is a single line with the string set_thread_count, one or more whitespace characters, and the thread count. The DB_CONFIG file is read when the database environment is opened, and hence it silently overrules configuration done before that time.
For more information, see DB_ENV->set_thread_count().