Space does not have a "hold" function, per se. It does, though, have "infinite" decay on several algorithms. It also has a "hot" switch that can be used during performance to toggle between 2 user-definable settings on any combination of 1 or more knobs. This can be setup to act exactly like a "hold" function, but it's much more flexible. Adding either an expression pedal or a set a auxillary switches greatly expands this functionality, as the expression pedal can be used to modify any combination of 1 or more knobs in real time, and an auxillary switch can be used to also toggle between the maximum and minimum values of the expression pedal.
The Space is one of the most flexible pedals I've even seen, especially when adding MIDI control. But what makes it so good is the sound quality. 12 algorithms each with 10 parameters that can be controlled in any combination between any values in real-time using the "hot" switch, aux switches, and/or an expression pedal, all stored in 100 presets, all available all the time. It sounds incredible and it's really easy to use.
Just FYI, the user manual is available for download. It does a good job of detailing its capabilities.