Is the 240x240 pixel limit in flicster the limit on the size units can be all together, or only the size limit for things to be displayed in flicster?

The 240x240 size limit is the maximum size of an individual frame.
And a frame can contain anything you like....providing it stays within that frame. :)
(But watch out for the right hand frame edge. If you don't leave a 2 or 3 pixel wide gap between your animation and this right hand frame edge, then 'ghost' images will appear in the following frames.
This only happens with the right hand frame edge....all the other sides of the frame can have an animation actually touching the frame edge without any problems. ;) )

Oh, and a 240x240 pixel animation is larger than 9 Civ3 terrain tiles (3 by 3).

Here is a screenshot of a 240x240 frame, with nine terrrain tiles for comparison.....

http://www.civfanatics.net/uploads4/frame_size.gif

A new animation of a nuclear blast would look good as 240x240 pixels, as it would cover almost all the surrounding tiles, instead of just the centre one.
(The current nuclear blast is 29 frames, each one 142x156 pixels)

Ok here's what I need to know then. I am trying to increase the size of a unit using the SBB tool, which allows you to increase the size of the frames using the alone formation. The original unit is pretty small, with a lot of extra, wasted space around it, and as such the tile is already 240x240. If I increase the size at all, it can't be viewed in flicster. Will it still work in game though?

Ah! I see your problem.

FLICster can enlarge frames, but it cannot reduce them.
And enlarging frames using Steph's SBB tool makes them so large that they are more than 240x240, so FLICster cannot show them.

I'm afraid that I don't know of a solution (apart from copying-'n-pasting each animation one-frame-at-a-time onto a new smaller storyboard....which I am sure you want to avoid!)

To be honest, I don't know what Civ3's limit is on frame size.
I suspect that animations with frame sizes larger than 240x240 would still work.....but that is only a wild guess.

Sorry, but apart from copying each animation into a smaller storyboard, I can't think of anything else. :(

I guess I'll just try it in game. Thanks anyway!