Clients who have paid their entire bill and have no ledger or margin debit with PLPL will get stocks once the exchange completes its payout activities on T+2. Else the stocks move into what is called a CUSA account where they need to be sold before T+7 unless the client has paid against his dues.
When there is a margin debit in the client account on T+2 day (lets say a sale done against unsettled stock), and the client has not pledged such stocks to PLPL, there may be a scenario where client may get into a shortfall (Sale done for T day purchases with no margin available) on margin. To prevent this situation, PLPL transfers stocks of clients where there is a margin shortfall in the account on T+2 and client has not pledged these stocks to PLPL till T+2.