I am working on an encoder that uses LSTM 
    def init_hidden(self, batch):
        '''
        used to initialize the encoder (LSTMs) with number of layers, batch_size and hidden layer dimensions
        :param batch:  batch size
        :return:
        '''
        return (
            torch.zeros(self.num_layers, batch, self.h_dim).cuda(),
            torch.zeros(self.num_layers, batch, self.h_dim).cuda()
        )

this is the code to initialize the LSTM, what does the batch_size represent for LSTM ? is the number of LSTMs used in the encoder ? . It is from social gan 7 algorithm.
Can someone please explain what it means?