Pathway/iTS TCP and Terminal Programming Guide

Handling Errors
Compaq NonStop™ Pathway/iTS TCP and Terminal Programming Guide—426751-001
10-2
SEND Statement Errors
SEND Statement Errors
This subsection suggests ways to handle the processing of SEND statement errors. You
can decide what is most appropriate to your particular application environment. For
additional information about SEND and SEND MESSAGE errors, refer to the Compaq
NonStop™ Pathway/iTS SCREEN COBOL Reference Manual.
Responding to SEND Errors
Tables 10-1 through 10-5 suggest how your requester ON ERROR code can respond to
error conditions arising from the execution of a SEND statement.
The specified numeric values represent the contents of the TERMINATION-STATUS
special register. The accompanying text indicates what the particular error code means.
For descriptions of what actions the system takes if you omit the ON ERROR clause,
refer to the Compaq NonStop™ Pathway/iTS SCREEN COBOL Reference Manual.
The codes in Table 10-1
reflect error conditions that could be transient; the problem
might go away spontaneously.
Because the error conditions might be recoverable, you can retry the failed SEND
statement, perhaps with a time delay, some finite number of times.
Before each retry, send a message to the terminal to let the operator know what is
happening (such as TRANSIENT ERROR, RETRYING).
If the SEND statement fails all of the allotted retries, the ON ERROR code should send
another message to the terminal telling the operator what is happening (such as
PERSISTENT ERROR, TERMINATING EXECUTION), log an error message to an
appropriate server, and then perform a STOP RUN statement.
Error 4 could be caused by the server’s allocating too little space for $RECEIVE
messages. To avoid this problem, the number of links specified in the server (for
example, in theCOBOL85 RECEIVE-TABLE OCCURS clause) should be greater than
the value specified in the SET SERVER MAXLINKS parameter in PATHCOM. The
default value for MAXLINKS is an unlimited number of links; therefore, to avoid this
problem, MAXLINKS must be set to a value.
Table 10-1. Requester SEND Errors for Transient Conditions
Numeric Value Meaning
1 Server class frozen
2,3 Resource unavailable
4 Link denied by PATHMON process or link rejected by server
12 I/O error
14 Maximum number of PATHMON processes has been reached
18 I/O error in attempt to communicate with the PATHMON process