elements of XHUGE structs

Hi Folks,

I do have some trouble with huge memory model and xhuge structures.

I wonder, how is it with structures of type xhuge, which constists of a lot of sub- structure types:

struct big
{
char amem[65000];
char bmem[65000];
char cmem[65000];
} xhuge st;

I do have functions get passed pointers to the substructures like this:

void dothat(char * pcStr) {}

I call the function like this:
dothat(&st.amem[8]);

Because of some strange errors in my system I wonder whether I should call the function with this cast:

dothat((char*)&st.amem[8]);

do get the xhuge type of struct st out of the way.

In common: how is it with assignments of a variable of type xhuge to one of type huge? I do this often in my code and the compiler gives no warning when doing that.

A little bit confused.
Mike