Choosing a system definition

Use the SYSTEM= parameter on the IMSCTRL macro to choose the type of system you want to define.

Use the IMSCTRL SYSTEM= parameter to identify the system you want to define:

DB/DC

Builds an IMS system that includes both the Database Manager (DB) and Transaction Manager (DC)

DBCTL

Builds an IMS system that includes only the Database Manager

DCCTL

Builds an IMS system that includes only the Transaction Manager

After you initially define your IMS system, you can later use the ON-LINE, CTLBLKS, and NUCLEUS options to implement changes. The ON-LINE, CTLBLKS, and NUCLEUS options require a cold start of the IMS online system to take effect.

For certain changes to your IMS system, you can take advantage of the online change method using the MODBLKS type of system definition. With the MODBLKS type of system definition, the changes are made active during the execution of the online system and do not require a restart operation.