How to change 'Maximum upload size exceeded' restriction in Shiny and save user file inputs?

I've recently learned that R Shiny programs impose a maximum size restriction for file uploads by default (I don't know what the size is exactly, but I'm guessing it's 5,000 KB). I'd like to remove this restriction. How can I do so, and what is there a general rule of thumb for the size of user uploads?

In addition, this is on another note, but related: how can I save fie inputs by the user BY session? For example, there would be a file prompt in the application, in which the user can upload a file. Then, when the user chooses the file to display, he can pick among the files he has uploaded. If he exits the session, the list clears.