I think the 'StackInitialised' flag is never set to a different value
and the 'tempArcStack' stack is initialized multiple times (every time
FBLatFirstPass() is called).

This is where it happens in HArc.c:

void ArcFromLat(ArcInfo *aInfo, HMMSet *hset){
[...]

   if(!StackInitialised)
      CreateHeap(&tempArcStack,"tempArcStore",MSTAK,
                1, 0.5, 1000,10000);
[...]


And I think it should be:


void ArcFromLat(ArcInfo *aInfo, HMMSet *hset){
[...]

   if(!StackInitialised) {
      CreateHeap(&tempArcStack,"tempArcStore",MSTAK,
                1, 0.5, 1000,10000);
      StackInitialised = TRUE;
   }
[...]