But they have similar mechanisms.
In Symbolics Genera 'programs' are called 'activities'. They can be started by keyboard shortcut, command, an application menu or by a general function, where the activity is an argument. Usually each 'activity' runs a command loop.
Additionally images have named lists containing functions, which are executed on certain event. For example if an image starts, a 'cold boot' list will be executed. If one has registered starting application programs (activity) - remember activities have names like editor, listener, mail client - they will be started by the operating system after a boot.
If a user logins on a Lisp Machine an init file gets executed. That init file can also contain general forms which start activities.
In addition, lisp programs (at least in these environments) don’t have “main”. I think it’s no big deal to start a program as “(foo)” but that’s surprisingly user hostile.
I worked with someone (who shall remain nameless) who ran in the same image for several years. There were random state variables scattered in his environment that affected the performance of his system in unreproducable ways.