Morality is a code of how to live on Earth, so I would have to say it's both necessary to hold some value essential to your being, but that context plays more of a significant role in the given situation that one makes a moral decision. By an essential value is that it's something you see as your highest value, like wanting to live, or to seek knowledge, or what have you. These values have a premise behind them for which one can use to make their decisions without ambiguity. Context is important, too, because it takes some perspective to understand what is right and what is wrong. Is it right to kill (no context)? Or it is right to kill in self-defense (a context given)? As you see, context can change the very nature of a situation greatly, making something that could be right and wrong at the same time, but is clearly one of the states that can be designated in regards to morality (right/wrong). With both in mind, it makes morality less a list of dos and don'ts, and more a process by which can figure out the truth of a given moral dilemma, without pleading to special cases.
-- Brede