CODE SIZE AND STACK CURRUPTION PROBLEM

Hi,

I am trying to develop an application in 16 bit. {Intel: Windows OS}

When I have code size(where i want to jump) of 11 k the lable jump is
happening ..
and when code size (where i want to jump) increases to 12 k the BOUCHS
gives error as
IRET: Top 6 bytes of stack are currupted.

jmp 0x2A00:0: jumps when code after 2a00 (linked using NASAM) is belOw
12 k

and same does not jump if code size after 2a00 icreases above 12k

IS THERE ANY RELATION BETWEEN THE CODE SIZE AND JUMP/STACK in 16 BIT?

Thanks in advance...