Ragnar the Viking from Melee Rulebook Example

[Frost Giant]

Ragnar, with spear and large shield, leather armor: Shield on left arm to catch hits, spear in right hand. Ragnar has initiative. Does he DROP the shield, because he needs both hands for the spear? I think he would have to in order to ready the spear for a thrust. He doesn't have time to sling it to his back, right? After the attack with the spear can he PICK UP the shield in the same turn?
I'm liking pole arms but haven't yet used them because of this. May be I'm just confused but I don't get how this works. Any help appreciated!
Thanks!