typedef struct 
{
     union
     {
          ULONG QueueDisabled: 1;
          ULONG MakeThreadsAsNecessary: 1;
          ULONG WaitMode: 1;
          ULONG WorkerCount: 29;
          LONG QueueWorkerInfo;
     };
} EX_QUEUE_WORKER_INFO, *PEX_QUEUE_WORKER_INFO;

Windows Vista Kernel Structures