/POINTER_SIZE=option
     /NOPOINTER_SIZE (D)

  Controls whether or not pointer-size features are enabled, and
  whether pointers are 32 bits or 64 bits long.

  The default is /NOPOINTER_SIZE, which disables pointer-size
  features, such as the ability to use #pragma pointer_size, and
  directs the compiler to assume that all pointers are 32-bit
  pointers.  This default represents no change over previous versions
  of the compiler.

  You must specify one of the following options:

    SHORT       The compiler assumes 32-bit pointers.

    32          Same as SHORT.

    LONG[=ARGV] The compiler assumes 64-bit pointers. If the ARGV option to
                LONG or 64 is present, the main argument argv will be an
                array of long pointers instead of an array of short pointers.

    64[=ARGV]   Same as LONG.

  Specifying /POINTER_SIZE=32 directs the compiler to assume that all
  pointers are 32-bit pointers.  But unlike the default of
  /NOPOINTER_SIZE, /POINTER_SIZE=32 enables use of the #pragma
  pointer_size long and #pragma pointer_size short preprocessor
  directives to control pointer size throughout your program.

  Specifying /POINTER_SIZE=64 directs the compiler to assume that all
  pointers are 64-bit pointers, and also enables use of the #pragma
  pointer_size directives.