In this paper, we study stability of M -compactness for l p sum of Banach spaces for 1 ≤ p < ∞. We also obtain a characterization of M -compact sets in terms of statistically maximizing sequence, a notion which is weaker than a maximizing sequence. Moreover, we introduce the notion of I-M -compactness of a bounded subset M of a normed linear space X with respect to an ideal I and show that it is equivalent to M -compactness for non-trivial admissible ideals.