struct HEAP_BUCKET_COUNTERS

typedef struct _HEAP_BUCKET_COUNTERS
{
     union
     {
          struct
          {
               ULONG TotalBlocks;
               ULONG SubSegmentCounts;
          };
          INT64 Aggregate64;
     };
} HEAP_BUCKET_COUNTERS, *PHEAP_BUCKET_COUNTERS;

Windows Vista Kernel Structures