[peteri]

The z80 version only supported recursion if it was specifically enabled so I suspect it tended use fixed locations for variables. Z80 support for a traditional stack frame for recursion isn't very good (although IX,IY with offsets could work).

[jonsen]

I’d guess that it used the old times trick of saving the return address by modifying the code of the called subroutine. A recursive call would then overwrite the primary callers return address.

[timonoko]

"Stack Frames"? I think they just pushed the current values of pertaining variables onto CPU stack upon entering a recursive function. Does Pascal even have lexical/dynamic binding issues? I do not think so.

[mavhc]

Cowgol doesn't have recursion at all anyway