The application stack and heap grow towards each other in the same region of memory. See Figure 7. In this run-time memory model, the heap is checked against the value of the stack pointer when new heap space is allocated, for example, when malloc() is called.

LOAD_FLASH ...
{
    ...
    ARM_LIB_STACKHEAP 0x20000 EMPTY 0x20000  ; Heap and stack growing towards
    { }                                      ; each other in the same region
    ...
}

The stack and heap are placed in separate regions of memory, see Figure 8. For example, you might have a small block of fast RAM that you want to reserve for stack use only. For a two-region model you must import __use_two_region_memory.

In this run-time memory model, the heap is checked against the heap limit when new heap space is allocated.

LOAD_FLASH ...
{
    ...
    ARM_LIB_STACK 0x40000 EMPTY -0x20000  ; Stack region growing down
    { }                                   ; 
    ARM_LIB_HEAP 0x28000000 EMPTY 0x80000 ; Heap region growing up
    { }
    ...
}