The Data Communication Control (DCCTL) environment

The Data Communication Control (DCCTL) environment allows you to use the IMS Transaction Manager independently of the IMS Database Manager.

DCCTL provides improved system performance in terms of throughput, system availability, and integrity. DCCTL can coexist with current IMS application programs and installed terminals.

The following scenarios involving DCCTL do not require modifications to your existing environment:

Application programs that access external database managers can use DCCTL without any modifications. For example, DCCTL can function as a front-end transaction manager for Db2 for z/OS®. Db2 for z/OS subsystems do not require modifications in order to run with DCCTL.
IMS exit routines and IMS application programs that access external subsystem resources in a DCCTL environment do not require modifications.
Global resource management is the same in a DCCTL environment as it is in a DB/DC environment.

The following procedures might require modifications for a DCCTL environment:

Operational procedures
The general procedure that is produced by the system definition
Application programs that contain a mixture of calls that access both external subsystems and IMS databases do require changes. DL/I calls result in a status code of AD.

Your existing system definition procedures support the generation of a DCCTL system. DCCTL executes with a collection of control blocks that identifies your data processing environment. These control blocks describe the system, data communication, and transaction manager components.

Using a DCCTL environment class system definition, you can generate a TM batch environment. Using TM batch, you can either take advantage of the IMS Batch Terminal Simulator (BTS) or access Db2 for z/OS systems. TM batch support allows only DBB and DL/I regions. It does not provide DL/I database capabilities.

Related reading: For more information on accessing Db2 for z/OS, see DB2® for z/OS Application Programming and SQL Guide.