Changing the Message Content

Message data is presented to exit IXZXIT01, through mapping macro IXZ$XPL, by a pair of fields:

XIT01_MESSAGE contains the address of the data
XIT01_MESSAGE_LEN contains the length of that data.

The data is transported as presented unless your exit routine changes that data. To change the data:

Obtain storage to contain the new copy of the data
This storage must be obtained from subpool 0. That is, do not specify a subpool. (IBM recommends using the STORAGE macro rather than $GETMAIN (for JES2) or AGETMAIN (for JES3) when obtaining this storage.)
Save the address of that storage in XIT01_MESSAGE_UPADDR
Save the length of that storage in XIT01_MESSAGE_UPLEN
Copy the data into the storage area and change the data as required
Set the indicator bit, XIT01_MESSAGE_UP, to inform JES XCF of the changes.

JES XCF transports the revised message rather than the original message data. Following message processing, JES XCF frees the storage obtained by this exit.