Debugging AMODE 64 C/C++ routines

This section provides specific information to help you debug AMODE 64 applications that contain one or more C/C++ routines. It includes the following topics:

Debugging C/C++ I/O routines
Using XL C/C++ compiler listings
Generating a Language Environment dump of a C/C++ routine
Finding C/C++ information in a Language Environment dump
Debugging example of C/C++ routines

There are several debugging features that are unique to C/C++ routines. Before examining the C/C++ techniques to find errors, you might want to consider the following areas of potential problems:

To prevent errors that may result from differences in LP64 default argument types, you should include function prototypes for all C/C++ function calls. For C/C++ runtime library functions, see z/OS XL C/C++ Runtime Library Reference.
Note: malloc() is an example of a RTL function which needs this prototype to work correctly in LP64 applications.
If you are using the fetch() function, see z/OS XL C/C++ Programming Guide to ensure that you are creating the fetchable module correctly.
If you are using DLLs, see z/OS XL C/C++ Programming Guide to ensure that you are using the DLL correctly.
Ensure that the entry point of the load module is CELQSTRT.
If you suspect that you are using uninitialized storage, you may want to use the STORAGE runtime option.
You should avoid:
- Incorrect casting
- Referencing an array element with a subscript outside the declared bounds
- Copying a string to a target with a shorter length than the source string
- Declaring but not initializing a pointer variable, or using a pointer to allocated storage that has already been freed
If a routine exception occurred and you need more information than the condition handler provided, run your routine with the following runtime options, TRAP(ON, NOSPIE) and TERMTHDACT(UAIMM). Setting these runtime options generates a system dump of the user address space of the original abend or program interrupt prior to the Language Environment condition manager processing the condition. After the system dump is taken by the operating system the Language Environment condition manager continues processing.