According to my awareness there is no command to give the share authority. In my previous client shop we use to go through 22 option from ISPF primary panel then there we have share option.
some things,(in my shop)
GENERIC or NORMAL or SPECIFIC(access type)
PDS name we have to provide which we are going to give the access.
after that we can go through 8 option and we can see the userids(we are all got the access)
if you send me the ISPF primary menu of your shop then I'll guide you.