Salary is a very touchy issue and there's several things to consider. One, that its a negotiation and you have to be very careful in your communications and diligent about protecting your own interests.
As an employee you're at a built-in disadvantage. Management knows everyone's salaries, you don't. Salaries are a closely guarded secret and they maintain that informational advantage against you.
So, you really have to look at industry averages for your role and decide if you are not being appropriately compd.
Now, about mgmt valuing you and not letting you go. First, NEVER threaten to leave. They may preempt that and cut you, or you'll go on a list of troublemakers. Managers have lists of people in their heads they would like to cut if given the opportunity. It's the people that get cut whenever there is a layoff, when teams have to be downsized.
It's important to understand mgmt's perspective. They have dozens of people in slots to get things done. No one person is indispensable, especially at the staff level where most programmers are. A slot goes open, they fill it. I've worked with managers with the biggest hearts, good guys, not mean spirited or unappreciative of their employees at all. They will not necessarily blink twice when an employee says they'll walk.
I would say, if you have a good case you're under compd, or unhappy. NICELY go to mgmt. If they won't do anything, get an offer from another company. Then you have the choice to just leave, or go back to your company and you have leverage and then its going to essentially be an ultimatum to keep you. But be very nice and polite about it.