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─────Run-Time Library───────────────────────────────────────────────────────
 
     The _alloca routine allocates <size> bytes from the program's
     stack. The allocated space is automatically freed when the calling
     function is exited.
 
     Observe the following restrictions when using _alloca:
 
        ■ When you compile with optimization on (either by default or
          by using one of the /O options), the stack pointer may not be
          restored properly in functions that have no local variables
          and that also reference the _alloca function. (This
          restriction does not apply to DOS32X.) The following program
          demonstrates the problem:
 
               /* Compile with CL /AM /Ox /Fc */
               #include <malloc.h>
 
               void main( void )
               {
                  func( 10 );
               }
               void func( register int i )
               {
                  _alloca( i );
               }
 
        ■ To ensure that the stack pointer is properly restored, make
          sure that any function referencing _alloca declares at least
          one local variable.
 
        ■ The pointer value returned by _alloca should never be passed
          as an argument to free.
 
        ■ The _alloca function should never be used in an expression
          that is an argument to a function.
 
     Return Value
 
     The _alloca routine returns a void pointer to the allocated space,
     which is guaranteed to be suitably aligned for storage of any type
     of object. To get a pointer to a type other than void, use a type
     cast on the return value. The return value is NULL if the space
     cannot be allocated.
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