ACUSQL_NO_AUTOCOMMIT explicitly turns off any auto-commit behavior that your ODBC driver may have. AUTOCOMMIT affects items such as record locking and the ability to roll back work. It is up to the driver vendor to determine whether a driver auto-commits work. If ACUSQL_NO_AUTOCOMMIT is set to 1, the runtime explicitly turns auto-commit off whether or not it is the default. If ACUSQL_NO_AUTOCOMMIT is set to 0, the runtime leaves the driver in its default state. Refer to the documentation provided by your driver vendor for default COMMIT behavior.