671e0429_n___Apache_Software_Foundation__Behavior
[Directive] s-max-age [Behavior] 
Means the same as max-age, except that it can only be enforced on shared caches and is ignored by private unshared caches. The age specified by s-max-age overrides the age specified by max-age. If using this directive, the proxy-revalidate directive must also be used.
Server HTTP Transport - Apache CXF Documentation - Apache Software Foundation