> My questions:
>
> 1. Is there official advice on setting the stack size when using
> Firebird Embedded (i.e. is the requirement of "/STACK:2097152"
> documented)?

No

> 2. Is 2 MB enough in all cases, or can we encounter a backup file which
> causes a stack overflow during restoring even with the 2 MB setting?

It can depens on "page buffers" setting if i not mistaken

> PS Part of the call stack below (Firebird 2.0.1.12855):

Is it during index creation ? It seems i saw such deep call stack one time...
Perhaps i will look at it again

Regards,
Vlad