These are archives generated by LArc, the predecessor to LHA, which uses the
-lz5- compression algorithm.  Found in larc333.exe (self extracting archive):

    http://ftp.riken.go.jp/pub/pc/simtelnet/msdos/arcers/larc333.exe

lz4.lzs             - Archive containing uncompressed (stored) file.
lz5.lzs             - Archive containing -lz5- compressed file.
sfx.com             - Self extracting LArc archive.
long.lzs            - Archive containing a large compressed file.
subdir.lzs          - Archive containing subdirectories.
initial.lzs         - Crafted -lz5- archive that dumps the full initial
                      contents of the history buffer from the start of
                      decompression. This archive is confirmed to work
                      correctly with LArc v3.33 and various versions of
                      LHA for DOS.

