Which is the maximum storage capacity to save documents in knowledge store for On Demand Customers.
All CA PPM On Demand Servers.
According to the documentation that SaaS provide.
Data Storage: All customers are provided with an initial setup of 40 GB of storage per deployed instance. Additional, incremental storage of 20 GB is made available for each set of 500 users or part thereof, over an initial set of 500 users.
So 20 GB it's the standard and it could change depending of the quantity of the users.