How can I set and keep the Arduino Stack size at increased size?

[maxgerhardt]

@ullix

But now the use of CONFIG_ARDUINO_LOOP_STACK_SIZE is marked with a squiggly line as identifier "CONFIG_ARDUINO_LOOP_STACK_SIZE" is undefined (I guess by the language server?).

If it’s defined in the build flags it should not be marked with a squiggly line. Try rebuilding the IntelliSense with Ctrl+Shift+P → Rebuild IntelliSense.