Cancels all or a selected subset of the Set Timer requests
    previously issued by the current image executing in a process.
    Cancellation is based on the request identification specified
    in the Set Timer ($SETIMR) service. If you give the same request
    identification to more than one timer request, all requests with
    that request identification are canceled.

    Format

      SYS$CANTIM  [reqidt] ,[acmode]

    C Prototype

      int sys$cantim  (unsigned __int64 reqidt, unsigned int acmode);