return DlInit(SvPV (initPath, PL_na));

(Unrelated to your actual question.)
PL_na is not much used these days. The perlapi documentation has this to say about it:

<quote>
PL_na A convenience variable which is typically used with "SvPV" when one doesn't care about the length of the string.
It is usually more efficient to either declare a local variable and use that instead or to use the "SvPV_nolen" macro.

STRLEN PL_na
</quote>

Cheers,
Rob