Page Layout ⇒ Vertical page alignment and oneside option in 'book' class

[vylain]

Hi there, here is my problem:

I have wrote a document using the book document class with the following options: 11pt, oneside, openany

I now want to make it double-sided so I removed the 'oneside' option.
When I remove it, the page vertical alignment changes drastically (and not in a good way for me).

With the option, some pages contain a large vertical space at the bottom because a large unsplittable element is next and does not fit in the page (e.g. long align environment).

Without the option, some even pages will have no vertical space at the bottom, but instead the vertical space between page elements will be increased, thus spreading unused vertical space all over the page.

Any idea why it is doing so ?
What options or parameters could change this behaviour ?

[vylain]

I just found a solution.
Use \raggedbottom before begin{document} and it works.
But, I still don't understand the change of behavior between the oneside and twoside options...

[Stefan Kottwitz]

In two-sided documents LaTeX tries to balance the page bottom such that their bottoms are in line. That's why the page content is stretched.

Stefan