Configuring IMS to execute rules on zRule Execution Server for z/OS

After you configure a zRule Execution Server for z/OS server group, you can optionally configure IMS to execute rules on a server instance.

Before you begin

Configure a zRule Execution Server for z/OS server group as described in Configuring topology 1: zRule Execution Server group with a shared console.
In Step 3: Customizing the z/OS configuration and runtime variables, customize the JCL variables that are listed in Configuration variables for configuring IMS to run rules on a zRule Execution Server for z/OS instance.

zRule Execution Server for z/OS supports IMS versions 11, 12, and 13.
IMS applications that use zRule Execution Server for z/OS for rules checking can run in Message Processing Regions (MPRs), Batch Message Processing (BMP) regions, or DLIBATCH regions.
IMS and zRule Execution Server for z/OS must run in the same logical partition (LPAR).

See Step 2: Choosing your topology for information about topology configuration options.

About this task

After you configure a zRule Execution Server for z/OS server group, you can configure IMS to execute rules on a server instance.

Procedure

Make the following changes to the execution JCL:
1. Add an HBRENVPR DD statement that specifies the zRule Execution Server for z/OS instance to be called by the IMS application.
  For example:
```
//HBRENVPR DD DISP=SHR,
// DSN=++HBRWORKDS++.SHBRPARM(HBRBATCH)
```
2. In the STEPLIB of the execution JCL, you must concatenate the SHBRIMS and SHBRLOAD libraries.
  For example:
```
// DD DSN=++HBRHLQ++.SHBRIMS,DISP=SHR
// DD DSN=++HBRHLQ++.SHBRLOAD,DISP=SHR
```
  Note: ++HBRHLQ++.SHBRIMS must come before ++HBRHLQ++.SHBRLOAD when the applications are using Dynamic Binding for the stub.
  
  Note: For optimum performance, consider putting the load library at the top of the STEPLIB or in the pageable link pack area (PLPA). For more information, see Choosing IMS options for performance .
If you are using IMS message processing regions (MPRs), complete the following step:
- Edit the DFSINTxx member of IMS.PROCLIB for your MPR region. Add the preinitialization routine HBRIPREI. The HBRIPREI preinitialization routine establishes the connection between the MPR and the zRule Execution Server for z/OS.
- Code the PREINIT parameter of DFSMPR as PREINIT=xx, where xx is the two-character suffix of the DFSINTxx PROCLIB member.
If you are using MPR, you must still include HBRCON and HBRDISC calls in your Message Processing Program (MPP); they do not affect the MPR connection to zRule Execution Server for z/OS but can be used for setting up other services if required.
Restart IMS to register the changes.
zRule Execution Server for z/OS must be started before IMS when it uses IMS Message Processing Regions.

If IMS is started before zRule Execution Server for z/OS, then restart the IMS Message Processing Region so that the HBRIPREI pre-initialization routine can initiate a connection with zRule Execution Server for z/OS.
Aside from the execution JCL changes, the use of the zRule Execution Server for z/OS from an IMS application program does not require any other setup in IMS. There are no special definitions in the IMS System definition nor in the IMS startup parameters. Everything else in IMS is business as usual.
For example, if the COBOL program that uses zRule Execution Server for z/OS is a BMP, then the definition in the IMS system definition for the BMP does not change. In addition, there are no changes in the PSB that is associated with the program.