In the stable Bootstrap 4.0.0 release, this is done using the sticky-top
class…
<div class="container">
<nav class="navbar navbar-light bg-light navbar-expand">
<a class="navbar-brand" href="#">Header</a>
...
</nav>
<div class="row">
<div class="col-8 content">
Content
</div>
<div class="col-4">
<div class="sticky-top">
<h4>Sticky menu</h4>
...
</div>
</div>
</div>
<div class="footer">
...
</div>
</div>
This works even in the height of the header/navbar, content, and footer are dynamic/unknown.