"With 10 players leaving obviously that leaves the squad very thin and we need quite a few more numbers to come into the club to give us some strength in depth," he says.
"So we are looking at lots of possibilities, though there are no two or three particular players I can give a clue to at the moment.
"But there are certain positions that we badly need to fill to give us a good balance throughout the team and so players are not playing in the wrong positions."
Glenn, though, is not anticipating a major sale of players, though he admits there will be some outgoings, and he adds: "First and foremost we have got to try very hard at keeping the majority of the squad together because without doubt it will be the quality of the players that we can put out next season that will give us the best possibility of bouncing back next time.
"But, as has been reported by the club while I have been out of action, we expect that there will be two or three that will be sold and the most important thing is that when that happens the players that come back in are good enough and motivated enough to make sure we have the season we want to have next year.
"The most important players are the ones that stay."
He is convinced that, despite demotion to the first division, players will still want to come to Upton Park.
"West Ham United is still a very attractive club to join and no one must forget that," he insists. "I don't think we will have any trouble attracting players to the club but it is the right ones that we want, ones that can integrate with the squad that is staying.
"It is important that we have enough numbers as well. There are 46 games plus the cup ones next year, and you can't possibly expect to get through that with 16 senior players - and at the moment we haven't got 16 senior players.
"There is an awful lot of work to be done in terms of bringing the right players in."
The choice of who to release this summer, and who would be offered new deals - namely Les Ferdinand, Steve Bywater, David Noble, and Daryl McMahon - was Glenn's alone and he confirms: "That was my decision. Some of the younger players that left obviously didn't play too much first team football and I wish them all the best.
"Some of the players played an awful lot of first team football and equally, I wish them good fortune at their new clubs where I hope they do extremely well.
"But it is time for us to move on and that is what we will be doing."
Glenn insists that injuries to key players played a massive part in West Ham's season and he adds: "There are facts but the cynics will say they are excuses. Now I want to concentrate on all the players coming back on the 1st of July and having a really strong pre-season so we can have a good start.
"It is just over three weeks since my operation and it is only at the start of the last week that I have started to really get my head round the coming season."