struct KERNEL_STACK_SEGMENT

typedef struct _KERNEL_STACK_SEGMENT
{
     ULONG StackBase;
     ULONG StackLimit;
     ULONG KernelStack;
     ULONG InitialStack;
     ULONG ActualLimit;
} KERNEL_STACK_SEGMENT, *PKERNEL_STACK_SEGMENT;

Windows Vista Kernel Structures