In the multiple stock trading, there are 30 unique stocks.

stock_dimension = len(train.tic.unique())

So the stock_dimension = 30

state_space = 1 + 2*stock_dimension + len(config.TECHNICAL_INDICATORS_LIST)*stock_dimension

state_space = 1+2*30+4*30 = 181

len(config.TECHNICAL_INDICATORS_LIST) = 4 because we have 4 technical indicators.