struct ACTIVATION_CONTEXT_STACK

typedef struct _ACTIVATION_CONTEXT_STACK
{
     PRTL_ACTIVATION_CONTEXT_STACK_FRAME ActiveFrame;
     LIST_ENTRY FrameListCache;
     ULONG Flags;
     ULONG NextCookieSequenceNumber;
     ULONG StackId;
} ACTIVATION_CONTEXT_STACK, *PACTIVATION_CONTEXT_STACK;

Windows Vista Kernel Structures