Regsister_Traceback('QUIT') #(control-\)

So if I get stuck in an infinite loop somewhere, pressing
ctl-\ instead of ctl-c will give me a traceback before exiting.  Optionally the trackback registration can take
a pointer to your own routine to call.  Based on the return
value of your own coded handler, Perl will then 
take an action based on the setup:
<code>
# sig, callback|disposition
# disposition = sign-bit=exit immediate
#  = (0) = exit
#  = 1-7 if (devel){stack trace} + ignore "X" times + exit
#  = 0x10 = message/nomessage
#  = 0x20 = 0=count in bottom nibble, 1=noexit
# = callback and status returns above val for further
# = processing