RET_XSTK compiler directive generating wrong code

I am using the following compiler directives for C51.exe CFLAGS = DB OE LARGE $(INCDIR) CODE RET_XSTK WL(1)

It looks like the generated code is incorrect. I have a TSK_create function with the following prototype

TSK_hndl_t TSK_create ( void *stack_ptr, uint16 stack_size, uint8 thread_priority, void (func)(void *), void *thread_arg ) reentrant;

because of the RET_XSTK directive the return address in SP is pushed into virtual stack ?C_XBP using ?C?CALL_XBP function and then when the function is about to exit, the return address from virtual address is retreived using ?C?RET_XBP function. Below I am listing the decompiled code.
?C?CALL_XBP:
MOV DPTR, #2
POP B
POP ACC
MOV R0, A
LCALL ?C?ADDXBP
POP ACC
MOVX @DPTR, A
INC DPTR
POP ACC
MOVX @DPTR, A
INC DPTR
MOV A, R0
PUSH ACC
PUSH B
RET

?C?RET_XBP:
MOV DPL, ?C_XBP + 1
MOV DPH, ?C_XBP
MOVX A, @DPTR
PUSH ACC
INC DPTR
MOVX A, @DPTR
PUSH ACC
MOV DPTR, #2
LJMP ?C?ADDXBP

It looks like there is a leakage in ?C_XBP and the return address are not retreived in the correct order.
I had to modify the ?C?RET_XBP function as follows
?C?RET_XBP:
MOV DPL, ?C_XBP + 1
MOV DPH, ?C_XBP
MOVX A, @DPTR
MOV B, A
INC DPTR
MOVX A, @DPTR
PUSH ACC
PUSH B
MOV DPTR, #0FFFEH
LJMP ?C?ADDXBP

My version of C51.exe is 6.02. Is this problem fixed in newer versions of the compiler or am I doing something stupid?