Operational Considerations 1
System Definition and Initialization
Before any CA IDMS/DB application program can use CA IDMS DLI Transparency, the CA IDMS DLI Transparency environment within CA IDMS/DB must be initialized. This is done using the initialization program called
System Generation Statements Defining IDMSDLTI
The system generation must contain an ADD PROGRAM statement to define IDMSDLTI:
ADD PROGRAM IDMSDLTI LANGUAGE IS ASSEMBLER REENTRANT REUSABLE.
The system generation must also contain an ADD TASK statement to define a task code that invokes IDMSDLTI:
ADD TASK IDMSDLTI INVOKES IDMSDLTI.
No CA IDMS/DB programs may use CA IDMS DLI Transparency before IDMSDLTI has been run. It is recommended that the system definition also contain an ADD AUTOTASK statement to automatically run IDMSDLTI immediately after CA IDMS/DB has come up.
ADD AUTOTASK IDMSDLTI INVOKED AT STARTUP PREEMPT.
Note that the PREEMPT option is included on the autotask definition. This is recommended so that no application programs that use CA IDMS DLI Transparency start before CA IDMS DLI Transparency initialization is completed.
The automatic scheduling of an IPSB associated with an application program (as defined in the CA IDMS DLI Transparency program definition table) is performed whenever the application program is linked to, either by the CA IDMS/DB system itself or from another application program.
- If an application program named in the CA IDMS DLI Transparency program definition table (DLPDTAB) is also associated with a CA IDMS/DB task code, then entering that task code in response to an ENTER NEXT TASK CODE message causes automatic scheduling of the IPSB before CA IDMS/DB passes control to the application program.
- The automatic scheduling is done during the linking process (that is, after the program issuing the LINK command gives up control but before the target program receives control) if an application program that isnotnamed in the DLPDTAB links to an application program thatisnamed in the DLPDTAB.
All application programs receiving control from a region controller (following the automatic scheduling) must be set up to receive the scheduled PCBs. This is the same as for CA IDMS DLI Transparency batch, IMS-DC, and IMS-DB.
Linking to lower level programs
An application program that receives control following the automatic scheduling may link (DC LINK) to lower level programs.
- If one or more scheduled PCBs are passed as parameters to the lower level program, the lower level program may issue DL1 calls using the passed PCBs.
- If a program is linked to as a lower level program, it must not be named in the DLPDTAB, since naming an application program in the DLPDTAB causes automatic scheduling to be performed. Automatic scheduling must not be performed on these lower level programs.
Automatic termination (TERM call) processing is performed for all application programs that have had an automatic scheduling call done. The termination processing is done at the time when the application program that had the automatic scheduling issues a DC RETURN. If the application program or any lower level programs it links to abnormally terminates (that is, the task thread is interrupted), the CA IDMS DLI Transparency run unit is abnormally terminated as well and any changes to the database are rolled back.