Placing linear dimension gives you the option to place them stacked or non-stacked. Sometimes when using "Linear size" option the dimension still are stacked.
From help file it states this regarding stacked dimensions:
If on, places stacked dimensions . If off, places in-line (unstacked) dimensions.
Enable this option to create “dog legs” in ordinate dimensions in cases where the text from a higher ordinate would overlap the text from a lower ordinate.
However, at times placing dimension without stacked dimension option on results in dimensions being stacked. This can be changed by making an adjustment to your dimension style settings.
Tool specific settings consists of controls for settings that affect individual dimensioning tools.Under each tool is a list of the settings for this tool. In this case under linear dimension tools there are individual setting that override dimension tool settings, i.e. size arrow, stacked location, custom linear to name a few.