order of operations matter, I think you'll want something like this? (check me, my linker syntax is bad):

```
SECTIONS
{
    .stack (NOLOAD): ALIGN(1024)
    {
        . = ALIGN(1024);
        __sguard = .;
        . = . + 1024;
        __eguard = .;
        __stackbot = .;
        . = . + 59K;
    } > RAM
}

ASSERT((ORIGIN(RAM) + LENGTH(RAM)) > __sguard, "");
ASSERT((ORIGIN(RAM) + LENGTH(RAM)) > __eguard, "");
ASSERT((_start_stack - __stackbot) > 59K, "");
```