@krishnamurthy, thanks for the reply.
1-  Do you know any sample code that showed how we can incorporate (stop) condition inside the LSTM?
2- Training subsequent is possible. However, I wanted to automatically use the previous output as the input of the next hidden unit.
3- Well, the first 20 dimensions are learnable. In the sequence S = [S0, S1, … , Sn] the first 20 dimensions are fixed, but they are different from the one of sequence S’ = [S’0, S’1, …, S’m].