DBCTL environment
The DBCTL environment is similar to the DB⁄DC environment; a DL⁄I region owns the databases to be processed. DL⁄I also exists in the DBCTL environment, although DL⁄I must run in its own address space. Database Recovery Control (DBRC) facilities, required for DBCTL, help to manage database availability, data sharing, system logging, and database recovery.
The greatest dissimilarity between DBCTL and DB⁄DC is that DBCTL does not support user terminals, a master terminal, or message handling. Therefore, no MPP regions exist. The BMP region is used only by batch applications and utilities. External program subsystems can, however, use an interface that does handle messages—a coordinator controller (CCTL). The same interface exists in the DB⁄DC control region, so it is possible to use a CCTL with a DB⁄DC environment. The interface between the CCTL and the control region is the database resource adapter (DRA). The DRA resides in the same address space as the CCTL.
The CCTL handles message traffic and schedules application programs, all outside the DBCTL environment. It passes database calls through the interface to the control region, which sends the calls to DL⁄I and passes results back through the interface to the CCTL.
The topics in this information that describe the IMS online system applies to both DB⁄DC and DBCTL. Exceptions are noted as not applicable to DBCTL.
The following figure shows an example of the DBCTL environment.
Even though the DBCTL environment includes no master terminal, you can still control the environment with IMS commands. The commands and command functions that control message processing are not operable here, but the remainder are. They can be entered through the MVS console or a secondary console. The control region recognizes commands by their first character, a slash (⁄). You can choose a different first character during system definition, or as an execution parameter.
Output messages from a command are sent to the console that entered the command. You can also specify other consoles to receive unsolicited output. These consoles are those that fall into the category you define using the IMS-generating macro, IMSCTRL.