typedef struct _HEAP_LOCAL_DATA
{
     SLIST_HEADER DeletedSubSegments;
     PLFH_BLOCK_ZONE CrtZone;
     PLFH_HEAP LowFragHeap;
     ULONG Sequence;
     _HEAP_LOCAL_SEGMENT_INFO SegmentInfo[128];
} HEAP_LOCAL_DATA, *PHEAP_LOCAL_DATA;

Windows Vista Kernel Structures