Writing routines for handling errors
You can handle most error conditions that might occur
while your program is running by using the ON EXCEPTION
phrase, ON SIZE ERROR phrase, or other language constructs.
But if an extraordinary condition such as a machine check occurs,
usually your application is abnormally terminated.
Enterprise COBOL and Language Environment® provide a way for a user-written program to gain control when such conditions occur. Using Language Environment condition handling, you can write your own error-handling routines in COBOL. They can report, analyze, or even fix up a program and enable it to resume running.
Most messages from the COBOL runtime are produced by signaling the corresponding
condition. This means that your error handler will get control. For I (Information) and W (Warning)
level conditions, you can simply percolate the condition, and the runtime will take care of
displaying the message and resuming the execution. In particular, this is required for various
compiler generated runtime diagnostics with a MSG option (for example,
SSRANGE(,MSG)) to work as intended.
When you write your own error-handling routines for an application, the COBOL programs must be compiled with appropriate compiler options. For more information, see OPTIMIZE.
To
have Language Environment pass control to a
user-written error program, you must first identify and register its
entry point to Language Environment. PROCEDURE-POINTER data
items enable you to pass the entry address of procedure entry points
to Language Environment services.