cc65 generated programs with the default setup run with the I/O area and the kernal enabled, which gives a usable memory range of $400 - $C038.
Special locations:
No conio support is currently available for the Lynx.
The Lynx "flabode" keys, Opt 1, Pause and Opt 2 are implemented using the conio interface. The only characters the keyboard is able to produce are 'R' for Restart (Opt 1 + Pause), 'F' for flip (Opt 2 + Pause), 'P' for pause, '1' for Opt 1, '2' for Opt 2, '3' for Opt 1 + Opt 2 and '?' for all keys down at the same time.
The C runtime stack is located at $C037 and growing downwards.
The C heap is located at the end of the program and grows towards the C runtime stack.