approx binary package in Ubuntu Xenial s390x

 Approx is an HTTP-based proxy server for Debian-style package archives.
 It fetches files from remote repositories on demand,
 and caches them for local use.
 .
 Approx saves time and network bandwidth if you need to install or
 upgrade .deb packages for a number of machines on a local network.
 Each package is downloaded from a remote site only once,
 regardless of how many local clients install it.
 The approx cache typically requires a few gigabytes of disk space.
 .
 Approx also simplifies the administration of client machines:
 repository locations need only be changed in approx's configuration file,
 not in every client's /etc/apt/sources.list file.
 .
 Approx can be used as a replacement for apt-proxy,
 with no need to modify clients' /etc/apt/sources.list files,
 or as an alternative to apt-cacher.

Source package