DB2 Server for VSE: System Administration

CICS/VSE Syncpoint Manager and the Task Related User Exit (TRUE)

In the DRDA2 VSE environment, DB2 Server for VSE uses CICS/VSE as its sync point manager. The environment can be shown as follows:

Figure 123. DB2 Server for VSE Distributed Unit of Work

This diagram shows how a workstation application might use DDCS for OS2 V2.3.1 to execute a distributed unit of work between 2 DB2 Server for VSE servers on different VM/ESA systems. Notice that DDCS registers itself with its own sync point manager. DDCS then establishes protected conversations with CICS AXE transactions. Each AXE transaction registers itself with a locally installed CICS/VSE sync point manager and CICS will perform any sync point logging and resynchronization activity. The AXE transactions use the VSE XPCC protocol to communicate with the DB2 Server for VSE servers 1 and 2.

DB2 Server for VSE also requires the use of a task-related user exit (TRUE) to interface with the CICS/VSE syncpoint manager and with the DB2 Server for VSE database manager as it participates in a coordinated commit or backout process. This interface is described in the CICS/VSE Customization Guide.

A separate task-related user exit program is enabled and started for each DB2 Server for VSE application server in support of distributed unit of work (two-phase commit). This is done by the AXE transaction under the following circumstances:

• DB2 Server for VSE database start-up parameter SYNCPNT=Y, and
• The conversation with the application requester is a protected basic conversation (synclevel 2), and
• The application starts doing some work (for example, begins using an agent), and
• The task-related user exit is not yet enabled.

The entry name of the task-related user exit program is 'ARI0xAXE', where x is 0->9, A->Z. x is the last character of a DB2 Server for VSE application server APPLID. The APPLID of a DB2 Server for VSE application server can be any of the following reserved DBNAMES:

• SYSARI00 to SYSARI09,
• SYSARI0A to SYSARI0Z.

Therefore, the corresponding entry name of the task-related user exit program is

• ARI00AXE to ARI09AXE,
• ARI0AAXE to ARI0ZAXE.

CICS transactions for managing DRDA task-related user exits:

DAXP

The DAXP transaction is a CICS transaction that sets the parameters that will be used when an AXE transaction subsequently autostarts DRDA TRUE (task-related user exit) support for an application server.

For more information on DAXP, see the DB2 Server for VSE & VM Operation manual.

DAXT

The DAXT transaction is a task-related user exit administration routine that is responsible for disabling DRDA support within CICS/VSE. It issues the EXEC CICS DISABLE command to disable a task-related user exit program.

For more information on DAXT, see the DB2 Server for VSE & VM Operation manual.