FKST reads cleanly across the Americas in this dataset, but the same letters can mean different things elsewhere (notably CST, EST, and IST overlap with non-American labels). Pin the IANA zone when the audience is international.
Atlantic/Stanley does not show an offset change in the next year, which makes FKST predictable for short-term scheduling. Predictable is not the same as permanent — civil-time rules still get changed by governments on relatively short notice.
For precise work, the safest equivalent of FKST is the exact IANA zone used by your city or system. Atlantic/Stanley sits at -03:00, behind UTC, which means daily logs in this zone reach a new calendar date after UTC does — relevant for date-aligned reports and billing cutoffs.
Within this single zone (Atlantic/Stanley, -03:00), FKST is unambiguous, so the abbreviation and the IANA zone effectively interchange.