6502: Stack-related things:

– software variable stack
– fixes for handling stack variables

docs/api/command-line.md

@@ -126,6 +126,10 @@ Allow using the IX register for other purposes.
 Allow using the IY register for other purposes.
 `.ini` equivalent: `iy_scratch`. Default: no.
 
+* `-fsoftware-stack`, `-fno-software-stack` –
+Use a software stack for stack variables.
+`.ini` equivalent: `software_stack`. Default: no.
+
 ## Optimization options
 
 * `-O0` – Disable all optimizations.

docs/api/custom-platform.md

@@ -80,6 +80,8 @@ Default: the same as `encoding`.
     
     * `iy_scratch` – allow using the IY register for other purposes, default is `false`
     
+    * `software_stach` – use software stack for stack variables, default is `false`
+    
     * `output_intel_syntax` – use Intel syntax instead of Zilog syntax, default is `true` for Intel 8080 and `false` otherwise