Chapter 9. Diagnosing Problems Within an Exec
Debugging Execs .......................111
Tracing Commands with the TRACE Instruction ...........111
TRACE C ........................111
TRACE E ........................112
Using REXX Special Variables RC and SIGL ............112
RC...........................112
SIGL ..........................113
Tracing with the Interactive Debug Facility .............113
Starting Interactive Tracing ..................114
Options Within Interactive Trace ................116
Ending Interactive Trace ...................116
This chapter describes how to trace command output and other debugging
techniques.
Debugging Execs
When you encounter an error in an exec, there are several ways to locate the error.
v The TRACE instruction displays how the language processor evaluates each
operation. For information about using the TRACE instruction to evaluate
expressions, see “Tracing Expressions with the TRACE Instruction” on page 37.
For information about using the TRACE instruction to evaluate host commands,
see the next section, “Tracing Commands with the TRACE Instruction”.
v Special variables, RC and SIGL, are set by the system to indicate:
– The return code from a command - (RC)
– The line number from which there was a transfer of control because of a
function call, a SIGNAL instruction, or a CALL instruction - (SIGL)
v The TSO/E command EXECUTIL TS (Trace Start) and EXECUTIL TE (Trace
End) control the interactive debug facility as do various options of the TRACE
instruction. For more information about interactive debug, see “Tracing with the
Interactive Debug Facility” on page 113.
Tracing Commands with the TRACE Instruction
The TRACE instruction has many options for various types of tracing, two of which
are "commands" or "c" and "error" or "e".
TRACE C
When you specify "trace c" in an exec, any command that follows is traced before it
is executed, then it is executed, and the return code from the command is
displayed.
When an exec without "trace c" issues an incorrect TSO/E command, the exec
ends with a TSO/E error message. For example, a LISTDS command specifies an
incorrect data set name.
"LISTDS ?"
This example results in the following error message.
© Copyright IBM Corp. 1988, 2001 111
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