Gender and queer theorists studying Shakespeare often discuss "As You Like It" in terms of gender-bendering or the maleability of gender. The layering and constructedness of gender in the play begin with its staging. As in classical drama, so to in Elizabethan drama, female roles were played by men. When Rosalind disguises herself as a man, therefore, what appears on stage is a male actor playing a female playing a man. This requires a superb performance, because theactor playing a cross-dressing Rosalind cannot simply act as a male would. Thus, despite the apparent performativity of gender, in fact, the humour of the play depends on the assumption that gender is innate rather than performative, and that a man playing a woman playing a man is not actually performing masculinity as a man would.
The work of gender theorist Judith Butler might be of use in your study of this, as would Greenblatt's notion of self-fashioning.