Is there an option out of the box for this? No, but you can certainly do it with CSS. Normally you really need to be designing your site around infinite scroll like Facebook, Twitter, etc.. all have. Effectively the component container in Joomla would be designed to scroll specifically and you can't have a non-static site footer. However yes it's possible to just limit this to the activity tab, but requires a decent amount of CSS to force it.
Below is an example of forcing the activity tab height out of the layout flow and making it adhere to its parent constraints. This will cause it to have a scrollbar if the tab contents are taller than its container.
Code:
.cbTabsMenu,
.cbTabsMenu .cbTabsMenuMain,
.cbTabsMenu .cbTabsMenuMain .cbTabsMenuContent,
.cbTabsMenu .cbTabsMenuMain .cbTabsMenuContent .cbTabPaneMenu {
height: 100%;
}
#cb_tabid_48 {
height: 100%;
overflow: auto;
position: relative;
}
#cb_tabid_48 .activityStream {
height: 100%;
width: 100%;
position: absolute;
top: 0;
left: 0;
}
Replace "48" with whatever the ID is of your CB Activity tab. This however will only extend down as far as the profile div goes. To force Joomla's component container and all other parent containers to also extend as far as they can within a page you'd need to adjust the first block of CSS to the following (Joomla 5 default template tested only).
Code:
main,
.cbProfileCanvasHome
.cbProfileCanvasHome .cbCanvasHomeLayout
.cbProfileCanvasHome .cbCanvasHomeLayoutMain
.cbTabsMenu,
.cbTabsMenu .cbTabsMenuMain,
.cbTabsMenu .cbTabsMenuMain .cbTabsMenuContent,
.cbTabsMenu .cbTabsMenuMain .cbTabsMenuContent .cbTabPaneMenu {
height: 100%;
}
This assumes a user is viewing their own profile and is doing so with the Profile (Home) layout. Please understand we don't provide custom coding outside of Business memberships. This is purely a simple example and there are several ways to go about this.