Writing your own node error program, Restrictions on the use of exec cics commands – IBM SC34-6814-04 User Manual

Page 527

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CSVTESBL

DS

A

NEPESBL - ESB locate routine

CSVTNEBD

DS

A

NEPNEBD - NEB delete routine

CSVTECUP

DS

A

NEPECUP - error count update
routine

Writing your own node error program

You can write your own NEP in any of the CICS-supported languages. However,
CICS-supplied NEP code is provided in assembler language only. The
communication area parameter list is supplied in assembler-language and C
versions. The names of the supplied source files, copy books, and macros, and the
libraries in which they can be found, are listed in Table 26.

Table 26. Supplied source files, copy books, and macros

Name

Type

Description

Library

DFHZNEP0

Program

Default node error
program (assembler
language)

CICSTS32.CICS.SDFHSAMP

DFHZNEPX

Source

Default NEP (embedded
by DFHZNEP0 via COPY
statement)

CICSTS32.CICS.SDFHSAMP

DFHSNEP

Macro

Sample NEP program
generator (assembler
language)

CICSTS32.CICS.SDFHMAC

DFHZNEPI

Macro

NEP interface generator
(for multiple NEPs)

CICSTS32.CICS.SDFHMAC

DFHNEPCA

Macro

Assembler-language
communication area

CICSTS32.CICS.SDFHMAC

DFHNEPCA

Copy
book

C-language
communication area

CICSTS32.CICS.SDFHC370

If you code in assembler language, you can use the sample NEP as a framework
on which to construct your own node error program.

Restrictions on the use of EXEC CICS commands

There are certain restrictions on the commands that a NEP can issue. The use of
any commands which require a principal facility causes unpredictable results,
and should be avoided
. In particular, you should not use commands which invoke
the following functions:

v

Terminal control. For example, issuing EXEC CICS DELAY may cause the CSNE
task to suspend and never resume, which can cause shutdown of the region to
hang. (“CEMT-type” commands, such as EXEC CICS INQUIRE TERMINAL, are
permissible)

v

BMS (except routing)

v

ISC communication (including function shipping). This includes START requests
for remote transactions. Such requests are not recommended because CSNE
(Node Abnormal Condition task) might become suspended while doing an
ALLOCATE to the remote system.

If you need to start a remote transaction, start a local transaction which starts a
remote one in turn.

Chapter 9. Writing a node error program

505

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