Using functions in the system programming C environment

If you do not want to use the z/OS® Language Environment® runtime library and the z/OS XL C runtime component within z/OS Language Environment the following functions are available in the SPC environment:

The following library functions are available as built-in so that they can be used without the runtime library:

Function Type	Function Name
Mathematical	`abs()`, `fabs()`
Memory manipulation	`memchr()`, `memcmp()`, `memcpy()`, `memset()`, `cds()`, `cs()`
String operations	`strcat()`, `strchr()`, `strcmp()`, `strcpy()`, `strlen()`, `strrchr()`
Wide character memory manipulation	`wmemchr()`, `wmemcmp()`, `wmemcpy()`, `wmemset()`

The built-in versions of these functions are available only if the appropriate header file (string.h, wchar.h, math.h, or stdlib.h) is included in the source file. The use of these functions is described in z/OS XL C/C++ Runtime Library Reference.

The memory management functions, including complete support for:
- The malloc() function
- The calloc() function
- The realloc() function
- The free() function
- The HEAP runtime option
The exit() function
The sprintf() function.
Note: The use of floating point conversion specifiers (e,E,f,g or G) is not supported without the Language Environment runtime.

Additional memory management functions are available in the system programming C environment, as follows:

__4kmalc(): to allocate page-aligned storage
__24malc(): to allocate storage below the 16MB line in ESA systems (where MB is 1048576 bytes) even when HEAP(ANYWHERE) is specified.

Storage allocated by these functions is not part of the heap, so freeing it is your responsibility. You can use the free() function to free the storage before the environment is terminated. Storage allocated using these functions is not automatically freed when the environment is terminated.

In this environment, low-level memory management functions and contents supervision (loading and deleting executable code) are supported by low-level routines that you can replace to support non-standard environments. This is described in Tailoring the system programming C environment.