## From win32.c
    if (mode == P_NOWAIT) {
    /* asynchronous spawn -- store handle, return PID */
    ret = (int)ProcessInformation.dwProcessId;
    if (IsWin95() && ret < 0)
        ret = -ret;

    w32_child_handles[w32_num_children] = ProcessInformation.hProcess;
    w32_child_pids[w32_num_children] = (DWORD)ret;
    ++w32_num_children;
    }

##</code><code>##

    case P_NOWAIT:  /* asynch + remember result */
    if (w32_num_children >= MAXIMUM_WAIT_OBJECTS) {
        errno = EAGAIN;
        ret = -1;
        goto RETVAL;
    }

##</code><code>##

C:\test>perl -le "for (1..100) {Win32::Spawn( $ENV{ComSpec},'/c echo>null', $pid );print qq[$_\tpid:$pid\t],$?==-1 ? $! : 'OK' };"
1       pid:5492        OK
2       pid:5256        OK
3       pid:1860        OK
...
93      pid:2236        OK
94      pid:2308        OK
95      pid:4012        OK
96      pid:4796        OK
97      pid:4636        OK
98      pid:4780        OK
99      pid:244 OK
100     pid:4800        OK