PERM inprogress 6th yr. H1B extension possible?

[Zephyr325]

 I completed my 6 years on H1-B in Feb 2016

 I got a 1 year H1-B extension (through Feb 28, 2017 ) when I switched to a diff employer , on approved PERM and I140 in progress status ( which i got when i was with my previous employer)

So my Current Visa is through Feb 28, 2017

My PERM (labor application) which is filed by my current employer is still in progress. PERM (labor ) filed in June 2016

My employer mentioned he will file a H1-B extension towards end of Feb 2017 (to buy time until PERM gets approved and I140 applied) .


Question :

 Is it legally valid to file a H1B extension that my employer plan to file toward 3rd week of Feb 2017 , in regular processing ?

 Will the H1B extension filed by my employer be valid and can i stay in USA until the decision comes back ?

Or

Will this be treated as a OVERSTAYED scenario and i will lose my opportunity to enter USA in future when another opportunity comes for me