CDC Guide for z/OS

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Configuring the IMS External Subsystem

The IMS synchronous ECCR operates as an IMS external subsystem.

To configure the IMS external subsystem of the ECCR, perform the following tasks:

If you do not have any external subsystems defined, add the SSM parameter to the EXEC statement in the IMS region JCL. Alternatively, specify the SSM parameter in the DFSPBxxx member, where xxx is the RGSUF value in the IMS region JCL.

In the IMS PROCLIB, add or modify the member that defines the external subsystem. The member name must be the four-character IMS subsystem ID followed by the SSM parameter value.

If you also specify the SSM parameter in MPP or BMP regions, change the members that contain the external subsystem definitions for both the control region and the dependent regions.

If you use the SSM parameter in the IMS control region, all of the MPP and BMP dependent regions have access to the subsystems defined in the member. If you plan to use the SSM parameter in both the IMS control region and the dependent regions, you must change both SSM members because the dependent region only has access to the subsystems that are defined in both members.

Do not include the external subsystem in any SSM member that is used by DL/I batch procedures and jobs.

In the external subsystem member, you can specify positional parameters that define the subsystem. Separate multiple parameters by using a comma (,).

The following table describes these parameters:

Parameter	Required	Description
SSN	Yes	Alphanumeric MVS subsystem name for the external subsystem. This name can be up to four characters long and must match the value of the PowerExchange Agent AgentID configuration parameter.
LIT	Yes	Alphanumeric language interface token. This value can be up to four characters long and must match the value of the PowerExchange Agent AgentID configuration parameter. SSN and LIT must have the same value.
ESMT	Yes	Alphanumeric name of the external subsystem module table. This value must be EDMCESMT.
RTT	No	Not in use. However, because the parameters are positional, you must include a comma as a placeholder for this field.
REO	Yes	One-character region error option code. The code determines the action IMS takes when an application program issues a request for external subsystem services before connection to the external subsystem is complete or when problems are encountered with the external subsystem. Options: R (the default) Q A PowerExchange requires option A , which causes IMS to terminate the application program with abend code U3047 and discard the transaction input.
CRC	No	A one-character command recognition character (CRC), which is required to issue external subsystem commands from IMS terminals or automated operator interface (AOI) applications. To be able to issue any of the IMS external subsystem commands that PowerExchange supplies, you must specify a value for this parameter. Enter any EBCDIC value except the forward slash (/), which is reserved for IMS use. When you issue an external subsystem commands, enter /SSR followed by the CRC value and then the command name, for example: /SSR `c`EDP-STAT . The external subsystem might require IMS user IDs and LTERM names to authorize you to issue external subsystem commands. For more information about authorization requirements, see the IBM IMS documentation.

The following example shows the fields that define the external subsystem for the IMS synchronous ECCR using the positional format:

PWXA,PWXA,EDMCESMT,,A,X

In this example, the PowerExchange AgentID is PWXA, the required REO value is A, and the CRC selected for the external subsystem commands is X.

The following example specifies an equivalent statement for the external subsystem using the keyword format:

SST=DB2,SSN=PWXA,LIT=PWXA,ESMT=EDMCESMT,CRC=X

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CDC Guide for z/OS

CDC Guide for z/OS

Configuring the IMS External Subsystem

Configuring the IMS External Subsystem