Q:

Shortcut for opening applications stack on dock bar

Is there any keyboard shortcut to open applications stack on dock bar?  
The idea is I want to be able to open any app without using mouse. 

A:

ctrl+fn+F3
..selects an item of the dock.  You can navigate using the arrow keys.  The selected item is the one that will be selected first the next time you use this shortcut. 
Once you've selected the Applications folder, the shortcut becomes for the next time:
ctrl+fn+F3+↩

BTW:
You can also use ctrl+fn+F2 to access menubar items. 

A:

Maybe you should try Alfred or QuickSilver.  Both of them give you the ability to open any applications quickly, not just the applications on dock. 

Play around with them and I am sure you will find your workflow on Mac more efficient.