[LCP] How get around "dereferencing pointer to incomplete type" error?

[geckoneS hilst]

I just want to put the include switch where it would be,
but I got a "derefencing pointer to implete type".. here is the code

-------------- FILE.C----------------------
#define STRCT_TYPE typeofstrct

#include <stdio.h>
// #include "libst.h" // <- I want it here

struct typeofstrct {
  struct strct * next;
  struct strct * prev;
  char * data;
} strct;

#include "libst.h"

int
main (void)
{
  strct.data = "Hello World";
  stack_strct_init (& strct, sizeof (strct) );
  printf ("%s\n", ((struct typeofstrct *) FirstItem) -> data);
  return 0;
}
-----------FILE.C---------------------------------------------
----------LIBST.H--------------------------------------------
#include <stdio.h>
#include <stdlib.h>
#include <string.h>

static void * FirstItem = NULL;
static void * LastItem  = NULL;
static void * StrctPtr  = NULL;
static size_t SizeOfStrct;

void
stack_strct_init (void * argptr, size_t siz)
{
  StrctPtr = argptr;
  SizeOfStrct = siz;

  void * newpool = malloc (SizeOfStrct);
  if (newpool == NULL)
	exit (EXIT_FAILURE);

  FirstItem = newpool;
  memcpy (FirstItem, StrctPtr, SizeOfStrct);
  ((struct STRCT_TYPE *) FirstItem) -> next = NULL;
  ((struct STRCT_TYPE *) FirstItem) -> prev = NULL;
}
----------LIBST.H--------------------------------------------