Int 21 Fn 81  - European Ms-dos 4.0 - "freeze" - Stop A Process            [D]

   AH = 81h
   BX = flag (00h freeze command subtree, 01h only specified process)
   CX = Process ID of head of command subtree

Return: CF clear if successful
   CF set on error
       AX = error code (no such process)
Desc:  temporarily suspend a process or a process and all of its children

Note:  if BX=0001h, this call will not return until the process is actually
     frozen, which may not be until after it unblocks from an I/O
     operation

See Also: AH=82h,AH=89h,AX=8E00h,INT 15/AX=101Dh