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Chapter 8. Writing a terminal error program
Considerations common to all user-replaceable programs
Note that the comments contained in “Chapter 5. General notes about
user-replaceable programs” on page 401 apply to this chapter.
This chapter contains information about the CICS terminal error program (TEP),
which handles error conditions for devices that use the TCAM DCB interface or the
sequential access method. Note that node error programs, not terminal error
programs, must be used for VTAM-supported devices. The chapter is divided
into three sections:
1. “Background to error handling for TCAM and sequential devices” is an
overview.
2. “The sample terminal error program” on page 417 describes the
CICS-supplied sample TEP. It contains:
v “Components of the sample terminal error program” on page 418
v “Structure of the sample terminal error program” on page 419
v “Sample terminal error program messages” on page 423
v “Generating the sample terminal error program” on page 425.
3. “User-written terminal error programs” on page 437 discusses factors you
need to consider when writing your own terminal error program. It contains:
v “Why write your own terminal error program?” on page 438
v “Restrictions on the use of EXEC CICS commands” on page 438
v “Addressing the contents of the communication area” on page 438
v “Addressing the contents of the TACLE” on page 441
v “Example of a user-written terminal error program” on page 445.
Background to error handling for TCAM and sequential devices
CICS terminal error handling is based on the assumption that most users want to
modify CICS operations in response to terminal errors. Because CICS cannot
anticipate all possible courses of action, the error-handling facilities have been
designed to allow maximum freedom for users to create unique solutions for errors
that occur within a terminal network.
The following CICS components are involved in the detection and correction of
errors that occur when TCAM terminals or sequential devices are used:
v Terminal control program (DFHTCP)
v Terminal abnormal condition program (DFHTACP)
v Terminal error program (DFHTEP).
These components are discussed in the following sections. (The corresponding
CICS components for logical units are discussed in “Chapter 9. Writing a node error
program” on page 449.)
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