User exit communications area structure

The user exit communications area contains two nodes:

The user exit communications area node
The message node

Table F-3 shows the structure of the user exit communications area.

**Table F-3: User exit communications area structure**
Attribute	Length (bytes)	Valid values	Description
APREPSW	1	Y (default) Allows replication of the transaction operation. N Prevents replication of the transaction operation.	Indicates whether the transaction operation should be replicated.
APFATAL	1	Y Shuts down LTM for MVS (sends a return code of 20 to Replication Extract). N (default) LTM for MVS continues operating.	Indicates whether LTM for MVS should issue a return code of 20 to Replication Extract.
APFUTURE	8	Not applicable	Reserved for future use.
APLOGMSG	4	x'00' (null pointer) Valid address of a message node	Points to a linked list of messages to be logged (see Table F-4: “Message node structure”).
APWKAREA	4000	Not applicable	This is a static work area for your user exit application. When the user exit places data in this area, the data is retained across multiple calls to the user exit.

Table F-4 shows the structure of the message nodes to which APLOGMSG can point.

**Table F-4: Message node structure**
Attribute	Length (bytes)	Description
APMSGNXT	4	A pointer to the next message structure or null.
APMSGTXT	4	A pointer to a null-terminated message string. (The null terminator is x'00'.)