Hello
Not sure I understand here.
First there is no chances that the application can work if you try to allocate the stack in flash.
Stack should be allocated in RAM.
Second, are you trying to program some data into flash from your application?
On HCS12, if you are running flash programming code from flash, you can only program banks located in another block. A block is a set of 4 flash pages (or banks).
Please refer to your hardware manual to check which pages are in block 0.
Check where the programming algorithm is located and where you are trying to program the code. If the two banks are allocated in the same block, it cannot work.
CrasyCat