The USERSTACKDPP3 directive changes compiler assumptions
about accesses to the user stack area and affects the address
generation of far, huge, and xhuge pointers. By
default, the user stack is located in the NDATA memory class
and is accessed using DPP2.
The USERSTACKDPP3 directive allows you to locate the user
stack in the IDATA or SDATA memory classes which are
accessed using DPP3. When relocating the user stack, some
changes must be made to the definition of the ?C_USERSTACK section in
the startup code (STARTUP.A66 or START167.A66) as
?C_USERSTACK SECTION DATA PUBLIC 'IDATA'
?C_USERSTACK SECTION DATA PUBLIC 'SDATA'
In addition, you must change the following line: