Int 31 Fn FF22  P - Causeway - "resmemdos" - Resize Conventional Memory B  [E]

   AX = FF22h
   BX = new size in paragraphs
   DX = initial selector for block

Return: CF clear if successful
   CF set on error
       AX = DOS error code (see #1366 at INT 21/AH=59h/BX=0000h)
       BX = maximum number of paragraphs available

Note:  this function will also fail if the block is expanded past a 64K
     boundary and the next selector is already in use

See Also: AX=FF21h,AX=FF23h,INT 21/AH=49h