-stl (Set archive timestamp from the most recently modified file) switch
Syntax
-stl
If -stl switch is specified, 7-Zip sets timestamp for archive file as
timestamp from the most recently modified file in that archive.
Examples
7z u a.7z -stl *.txt
Commands that can be used with this switch
a (Add),
d (Delete),
rn (Rename),
u (Update)