typedef struct _POOL_DESCRIPTOR
{
     POOL_TYPE PoolType;
     ULONG PoolIndex;
     LONG RunningAllocs;
     LONG RunningDeAllocs;
     LONG TotalPages;
     LONG TotalBigPages;
     ULONG Threshold;
     PVOID LockAddress;
     VOID * * PendingFrees;
     LONG ThreadsProcessingDeferrals;
     LONG PendingFreeDepth;
     ULONG TotalBytes;
     ULONG Spare0;
     LIST_ENTRY ListHeads[512];
} POOL_DESCRIPTOR, *PPOOL_DESCRIPTOR;

Windows Vista Kernel Structures