IMS ALTPCB enhancement for IMS Connect

In IMS 15.2, with APAR PH39434 and PH39438, an IMS ALTPCB output triggered by an IMS Connect commit-then-send send-receive call can be sent back to the initiating IMS Connect client.

By default, when IMS Connect is identified as the destination of an IMS ALTPCB output message, IMS queues the output to a TPIPE hold queue. An IMS Connect client is able to retrieve this ALTPCB output with a Resume TPIPE call. However, it might be difficult for an IMS Connect client application to know whether IMS would generate an I/O PCB output or an ALTPCB output. In addition, an ALTPCB output message generated by an IMS shared-queues back-end system has an affinity of the back-end system.

This message affinity prevents the Resume TPIPE call that is sent to the front-end system from retrieving the IMS ALTPCB output message unless IMS Connect activates the super member function. This default behavior of handling the IMS ALTPCB output for IMS Connect complicates the TCP/IP application development for getting an ALTPCB output message.

With APAR PH39434 and PH39438, IMS introduces a new function, SENDALTP, for IMS Connect customers to obtain an ALTPCB output without issuing Resume TPIPE calls. When the SENDALTP function is activated, if IMS receives a commit-then-send send-receive call from IMS Connect, an ALTPCB output triggered by the input transaction can be sent back to the initiating IMS Connect client by using the input TPIPE name.

The supported ALTPCB output message flow is: TCP/IP APP → IMS CONNECT X → IMS → IMS CONNECT X → TCP/IP APP. This SENDALTP function won't work if the ALTPCB output is routed to a different IMS Connect client or to a non-IMS Connect destination using OTMA destination descriptor or OTMA DFSYDRU0 user exit.

You can activate the SENDALTP function with two methods: data store level activation and message level activation.

With data store level activation, the SENDALTP function can be activated for all the commit-then-send send-receive calls from this IMS Connect data store. You can enable the data store level activation with the following methods:

Using the CREATE IMSCON command or the UPDATE IMSCON command
Specifying SENDALTP in IMS Connect HWSCFGxx member
Specifying SENDALTP parameter in OTMA client descriptor in DFSYDTx PROCLIB member

The message level activation can be set for a specific IMS Connect commit-then-send send-receive request through a user-written IMS Connect client, IMS OTMA destination descriptor, or IMS DFSYDRU0 exit.

Changes to defining IMS

The following descriptors are enhanced with the SENDALTP= keyword:

The OTMA client descriptor in the DFSYDTx member of the IMS PROCLIB data set
The OTMA destination descriptor in the DFSYDTx member of the IMS PROCLIB data set
The DATASTORE statement in the HWSCFGxx member of the IMS PROCLIB data set
The HWS statement in the HWSCFGxx member of the IMS PROCLIB data set

The TPIPE=, SMEM= and EXIT= keywords in the OTMA destination descriptor in the DFSYDTx member of the IMS PROCLIB data set are enhanced with descriptions for the SENDALTP= keyword.

Changes to troubleshooting for IMS

For a list of the messages and codes that are new or changed for this enhancement, see the IMS messages and codes row in the table in Documentation changes.

For a complete list of all of the new, changed, and deleted messages, and abend codes in IMS 15.2, see Message and code changes in IMS 15.2.

Changes to commands

The following commands are enhanced to have the SENDALTP keyword and its description added:

CREATE OTMADESC command
UPDATE OTMADESC command
VIEWHWS command
VIEWDS command
CREATE IMSCON TYPE(DATASTORE) command
UPDATE IMSCON TYPE(CONFIG) command
UPDATE IMSCON TYPE(DATASTORE) command
QUERY IMSCON TYPE(CONFIG) command
QUERY IMSCON TYPE(DATASTORE) command

For a list of the commands that are new or changed for this enhancement see the IMS commands row in the table in Documentation changes.

Documentation changes

The following table lists the publications that contain new or changed topics for the New function name enhancement. Publications that are not impacted by this enhancement are not included in the table.

Table 1. Links to topics that have new or changed content for this enhancement
Publication	New or changed topics
Release planning	General planning information for IMS 15.2 Command changes in IMS 15.2 Changed messages and codes for IMS 15.2 IMS 15.2 enhancements IMS 15.2 Transaction Manager continuous delivery functions IMS ALTPCB enhancement for IMS Connect (new) (this topic)
System definition	Members of the IMS PROCLIB data set DFSYDTx member of the IMS PROCLIB data set OTMA client descriptor syntax and parameters OTMA destination descriptor syntax and parameters HWSCFGxx member of the IMS PROCLIB data set DATASTORE statement HWS statement
Communications and connections	IMS Connect and TCP/IP communications IRM structures for IMS Connect client messages Format of user portion of IRM for HWSSMPL0, HWSSMPL1, and user-written message exit routines OTMA header fields used by IMS Connect OTMA message-control fields used by IMS Connect OTMA state data fields used by IMS Connect Open Transaction Manager Access (OTMA) Using shared queues with OTMA Retrieving ALTPCB output from a back-end IMS system Delivering ALTPCB output without RESUME TPIPE calls for IMS Connect (new) OTMA message prefix Message-control information section Explanation of OTMA message-control information fields State data section Server-Available and Client-Bid commands Transaction and callout messages
IMS messages and codes	DFS messages DFS2385E
IMS commands	IMS commands CREATE IMSCON commands CREATE IMSCON TYPE(DATASTORE) command CREATE OTMADESC command Query IMSCON commands QUERY IMSCON TYPE(CONFIG) command QUERY IMSCON TYPE(DATASTORE) command QUERY OTMADESC command Update IMSCON commands UPDATE IMSCON TYPE(CONFIG) command UPDATE IMSCON TYPE(DATASTORE) command UPDATE OTMADESC command IMS component and z/OS commands IMS Connect WTOR commands VIEWDS command VIEWHWS command
Exit routines	Transaction Manager exit routines OTMA Destination Resolution user exit (DFSYPRX0 and other OTMAYPRX type exits) OTMA User Data Formatting exit routine (DFSYDRU0)