$ ./pants help-advanced compile.zinc | grep -A3 'zinc-incremental'

--[no-]compile-zinc-incremental (default: True)
    When set, zinc will use sub-target incremental compilation, which
    dramatically improves compile performance while changing large targets. When
    unset, changed targets will be compiled with an empty output directory, as
--
--[no-]compile-zinc-incremental-caching (default: False)
    When set, the results of incremental compiles will be written to the cache.
    This is unset by default, because it is generally a good precaution to cache
    only clean/cold builds.