The feedback code is an optional parameter of the Language Environment callable services. (For COBOL/370 programs, you must provide the fc parameter in each call to a Language Environment callable service. For C/C++, Enterprise COBOL for z/OS, COBOL for OS/390 & VM, COBOL for MVS & VM, and PL/I routines, this parameter is optional. For more information about fc and condition tokens, see z/OS Language Environment Programming Guide.
When you provide the feedback code (fc) parameter, the callable service in which the condition occurs sets the feedback code to a specific value called a condition token.
The condition token does not apply to asynchronous signals. For a discussion of the distinctions between synchronous signals and asynchronous signals with POSIX(ON), see z/OS Language Environment Programming Guide.
When you do not provide the fc parameter, any nonzero condition is signaled and processed by Language Environment condition handling routines. If you have registered a user-written condition handler, Language Environment passes control to the handler, which determines the next action to take. If the condition remains unhandled, Language Environment writes a message to the Language Environment message file. The message is the translation of the condition token into English (or another supported national language).
Language Environment provides callable services that can be used to convert condition tokens to routine variables, messages, or signaled conditions. Table 1 lists these callable services and their functions.
| Description | |
|---|---|
| CEEMSG | Transforms the condition token into a message and writes the message to the message file. |
| CEEMGET | Transforms the condition token into a message and stores the message in a buffer. |
| CEEDCOD | Decodes the condition token; that is, separates it into distinct user-supplied variables. Also, if a language does not support structures, CEEDCOD provides direct access to the token. |
| CEESGL | Signals the condition. This passes control to any registered user-written condition handlers. If a user-written condition handler does not exist, or the condition is not handled, Language Environment by default writes the corresponding message to the message file and terminates the routine for severity 2 or higher. For severity 0 and 1, Language Environment continues without writing a message. COBOL, however, issues severity 1 messages before continuing. CEESGL can signal a POSIX condition. For details, see z/OS Language Environment Programming Guide. |
There are two types of condition tokens. Case 1 condition tokens contain condition information, including the Language Environment message number. All Language Environment callable services and most application routines use case 1 condition tokens. Case 2 condition tokens contain condition information and a user-specified class and cause code. Application routines, user-written condition handlers, assembler user exits, and some operating systems can use case 2 condition tokens.
- X'0003' is severity.
- X'032D' is message number 813.
- X'59' are hexadecimal flags for case, severity, and control.
- X'C3C5C5' is the CEE facility ID.
- X'00000000' is the ISI. (In this case, no ISI was provided.)
If a Language Environment traceback or dump is generated while a condition token is being processed or when a condition exists, Language Environment writes the runtime message to the condition section of the traceback or dump. If a condition is detected when a callable service is invoked without a feedback code, the condition token is passed to the Language Environment condition manager. The condition manager polls active condition handlers for a response. If a condition of severity 0 or 1 remains unhandled, Language Environment resumes without issuing a message. Language Environment does issue messages, however, for COBOL severity 1 conditions. For unhandled conditions of severity 2 or greater, Language Environment issues a message and terminates. For a list of Language Environment runtime messages and corrective information, see z/OS Language Environment Runtime Messages.
If a second condition is raised while Language Environment is attempting to handle a condition, the message CEE0374C CONDITION = <message no.> is displayed using a write-to-operator (WTO). The message number in the CEE0374C message indicates the original condition that was being handled when the second condition was raised. This can happen when a critical error is signaled (for example, when internal control blocks are damaged).
If the output for this error message appears several times in sequence, the conditions appear in order of occurrence. Correcting the earliest condition can cause your application to run successfully.