Archanians 30 κέχηνα perfect in form, present in meaning?

[ἑκηβόλος]

στένω κέχηνα σκορδινῶμαι πέρδομαι,

1. Is Aristophanes treating κέχηνα as a verb like ἕστηκα and ὄδωδα, perfect in form and present in sense?
2. If 1. is yes, I that the regular usage?
3. If 2. is no, then is he here saying, "I sit / stand with my mouth gaping open" = "I give a really big (10 second) yawn"?

[anphph]

The usual force of the perfect is a present consequence of a past action. χάσκειν means "to open one's mouth", the present consequence of having opened one's mouth in the past is having one's mouth open (now).

Edit: For what it matters, both the instances in LSJ of χάσκειν as "yawning from weariness, ennui, or inattention" function with the present stem.