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in the local system. If the requested terminal is remote, the terminal allocation
program ships an ATI request to the remote system, which initiates transaction
routing back to the local system.
For guidance information about ATI, refer to the CICS Intercommunication
Guide.
‘Terminal not known’ condition
The ‘terminal not known’ condition arises when an ATI request is made for a
terminal not known in the region. An ATI request can occur in the AOR for a
SHIPPABLE terminal before any transaction routing has taken place for the
terminal, and so before the definition of the terminal can have been shipped
from the TOR to the AOR.
If the ‘terminal not known’ condition occurs, both the interval control program
and the terminal allocation program reject the transaction-initiation request as
‘TERMIDERR’.
The exits
To deal with the ‘terminal not known’ condition, CICS provides global user exits in
the interval control and terminal allocation programs:
XICTENF
In the interval control program
XALTENF
In the terminal allocation program.
CICS drives the XICTENF exit when the ‘terminal not known’ condition occurs after
the interval control program has been invoked by an EXEC CICS START command.
CICS drives the XALTENF exit when the ‘terminal not known’ condition occurs after
the terminal allocation program has been invoked by the transient data trigger level
or the interval control program. Note that an EXEC CICS START command could
result in both exits being invoked.
The exit program must indicate whether the terminal exists on another system and,
if so, on which one. CICS passes data to the exit program to help establish this
information. You can use the same exit program at both exit points. CICS supplies a
sample exit program, DFHXTENF (see Figure 2 on page 231), that can be used at
both exits and that can deal unchanged with some typical situations.
The exits are designed to deal with ‘terminal not known’ conditions that occur in
CICS regions other than the TOR. For a TOR/AOR pair, enable the exit program in
the AOR. The exits cannot deal with a ‘terminal not known’ condition in the TOR
and the exit program should not normally be enabled there. However, if more than
one TOR exists, you may need to enable the exit program in each TOR to deal with
requests for terminals owned by other TORs. In this case, the exit program must
recognize terminals that should be owned by this system and reject the requests
(‘UERCTEUN’). Although the exit provides as much data as possible, the logic of
your program depends entirely on your system design. A simple solution to the most
complex case would be to make the name of each terminal reflect the netname or
sysid of its owning region.
Data returned by exit: The exit program must set a return code in register 15 as
follows:
UERCTEUN
Terminal does not exist
Chapter 1. Global user exit programs 225