This is part of Win16 API which allow to create versions of program from one source code to run under OS/2 and Win16. Under OS/2 program can be running under Win-OS/2 if program is Windows NE executable, and with help on Windows Libraries for OS/2, if it is OS/2 NE executable. Here is a WLO to OS/2 API mapping draft
Frees a local memory object and invalidates its handle.
HLOCAL WINAPI LocalFree( HLOCAL hMem );
hMem – Handle to the memory object to free.
Returns NULL if the function succeeds.
Returns the original handle if it fails. Call GetLastError for more information.
After freeing, the handle is no longer valid.
If hMem is NULL, the function does nothing and returns NULL.
It is safe to free a locked block, but doing so may cause memory corruption; always unlock before freeing.
In debug versions of Windows, freeing a locked block may generate a diagnostic message.
if (LocalFree(hMem) != NULL) { // error handling }
push hMem call LocalFree cmp ax, 0 ; success if AX == 0