INITIAL_SP holds the initial Stack Pointer value so
that we know where to reset it on ABORT

CURRENT points to the last dict entry.

HERE points to current write offset.

IP is the Interpreter Pointer

PARSEPTR holds routine address called on (parse)

C<* holds routine address called on C<. If the C<* override
at 0x08 is nonzero, this routine is called instead.


                                                        (cont.)