If sv is not NULL, it specifies the address of a structure
    containing a pointer to a handler routine and mask to be used
    when delivering the specified signal, and a flag indicating
    whether the signal is to be processed on an alternative stack.
    If sv->onstack has a value of 1, the system delivers the signal
    to the process on a signal stack specified with sigstack.

    The sigvec function establishes a handler that remains
    established until explicitly removed or until the image
    terminates.

    The sigvec structure is defined in the <signal.h> header file:

    struct sigvec
       {
          int   (*handler)();
          int   mask;
          int   onstack;
       };

    See the "Error and Signal Handling" chapter of the HP C RTL
    Reference Manual for more information on signal handling.