Defining online applications
You can use either IMS commands or the PGMCREAT user exit with dynamic resource definition (DRD) enabled or the IMS system definition macros to define online applications.
IMS online applications consist of individual programs that are scheduled to process transactions. Scheduling must be invoked by JCL for batch message programs. You must identify to the control program both the available programs and the transactions that they process. You must also identify the entire set of databases that the applications can refer to.
If you want data sharing to be supported, be sure that you understand the interaction between the IMSCTRL and DATABASE macro statements and parameters.
The table that follows lists database and application macros, how many are coded, and the purpose of the macro. Although these macros are optional (because of DRD), you must ensure that the appropriate database and application control blocks are available to your IMS system. Otherwise, your IMS system might not work as you want it to.
| Macro | Number of macros coded | Purpose of macro |
|---|---|---|
| APPLCTN | One per PSB | Names the application program that processes the transaction codes specified on the TRANSACT statements. The TRANSACT macro follows the APPLCTN macro in the stage 1 system definition input stream. |
| DATABASE | One per HSAM, HISAM, HDAM, or PHDAM database; 2 per HIDAM or PHIDAM database; 1 per secondary index database that refers to another database; 1 per MSDB, DEDB | Defines all databases that IMS online control program (and DBCTL environment) manages. |
| RTCODE | One or more per APPLCTN macro | Specifies the routing codes that the Fast Path Input Edit/Routing exit routine (DBFHAGU0) uses to select a Fast Path application program. |
| TRANSACT | One or more per APPLCTN macro; 0 for non-message BMP regions | Names the transaction codes to be processed by the application program that is specified on the APPLCTN macro. The APPLCTN macro precedes the TRANSACT macro in the stage 1 system definition input stream. |
For a DBCTL environment, you define application programs only for BMP regions by using the APPLCTN macro. For an application program that runs in a CCTL or uses the ODBA interface, use the APPLCTN macro to define the PSB names that the appropriate applications require. The TRANSACT macro is not used in defining a DBCTL system.
The PGMCREAT user exit is valid for DB/DC, DBCTL, and DCCTL environments with DRD enabled. The user exit can specify the dynamical creation of runtime program resources for application programs that run in BMP and JBP dependent regions.