The 28-year-old was given the green light after a final check-up by the specialist who operated to repair the damaged ligaments in his right shoulder following a challenge by Hamilton defender Mark McLaughlin four months ago.
The injury on March 1 at New Douglas Park ended Stack's comeback after just five matches, the much-travelled goalie having spent almost six months sidelined as he battled against a nagging back problem and also brought his season to a premature end.
But now the former Republic of Ireland Under-21 is desperate to begin his fight with Mark Brown for the right to wear the gloves when Hibs face Celtic at Easter Road in their opening match of the new SPL season on Sunday, July 24.
And Stack believes that could come in just six days' time when Colin Calderwood's side make the short trip to West Lothian for their second warm-up match.
Having been restricted to working with goalkeeping coach Scott Thomson over the past week, Stack today told the Evening News: "All is good, I'm back in full training as of Friday and hopefully I can play some part in the Livingston game."
Meanwhile, Ian Murray has claimed Hibs' "unique" family-like atmosphere has made it easy for former stars such as Garry O'Connor and Ivan Sproule to return to Easter Road. Like Murray himself, Scotland striker O'Connor and and Northern Ireland winger Sproule have signed on for a second spell in the Capital with the Hibs skipper insisting few clubs would welcome back ex-players as readily as the Edinburgh outfit.
However, Murray was adamant that neither O'Connor or Sproule was back in a comfort zone, revealing that the pair, along with boss Colin Calderwood's third summer signing, MK Dons defender Sean O'Hanlon, they were "raring to go".
The utility man said: "It's been good to see Garry again, I was rooming with him while we were training down in Peebles last week and you forget how funny he can be. But he's raring to go, really hungry like Ivan.
"They aren't here just to sit back and relax, it's going to be a tough season and, like Sean, they are looking sharp and just want to get on with it."
Both O'Connor and Sproule have described rejoining the club as "coming home", a view Murray understands having himself departed for Rangers before returning via Norwich City during Mixu Paatelainen's time as manager as did striker Derek Riordan - now seeking a new club - after moving to Celtic.
Murray said: "I think the number of players coming back shows how special it is. People at the club welcome you back and not many clubs would take so many back after being away, especially a couple of us who went to Glasgow.
"Garry and Ivan probably had options elsewhere but there's something special that draws you back."
And Murray insisted it was the little things which counted most, revealing how a request to Calderwood for permission for his wife to bring their son Lewis to the training camp for half an hour on his first birthday resulted in a card, birthday cake and the entire squad and backroom staff singing Happy Birthday to the toddler. Murray added: "Just little touches like that make it a family place and a good place to play football."