Finding the dll path at runtime

Hi,
I am using xamarin forms and have built a plugin library to load dlls at runtime....but have run into a bit of an issue trying to determine the applications dll path at runtime....does anyone know how to do this?

NOTE: I am after a function that will work on android/winphone and ios if possible. I am using PCLStorage - but that has the document folders not the dll folders.

Thanks

Mike