how to force setjmp/longjmp

Hi!
I try to use setjmp/longjmp instructions, but application fails with
KERN-EXEC 3. Code is very simple:
int Main()
{
     jmp_buf  jump_buffer;
     if ( setjmp( jump_buffer ) == 0 )
     {
       longjmp( jump_buffer, 1 );
     }
     return 0;
}
Anybody used setjmp/longjmp? Share experience, please. 
Thanks.