Basically (and very roughly), the standard paths on Unix are:
/bin&/sbinfor vital programs for the OS, sbin being for administrators only ;/usr/bin&/usr/sbinfor not vital programs, sbin being for administrators only ;/varfor living data for programs. It can be cache data, spool data, temporary data (unless it's in/tmp, which is wiped at every reboot), etc. ;/usr/localfor locally installed programs. Typically, it hosts programs that follow the standards but were not packaged for the OS, but rather installed manually by the administrator (using for example./configure && make && make install) as well as administrator scripts ;/optfor programs that are not packaged and don't follow the standards. You'd just put all the libraries there together with the program. It's often a quick & dirty solution, but it can also be used for programs that are made by yourself and for which you wish to have a specific path. You can make your own path (e.g./opt/yourcompany) within it, and in this case you are encouraged to register it as part of the standard paths ;/etcshould not contain programs, but rather configurations.
If your programs are specific to the services provided by the service, /srv can also be a good location for them.