Hi Teja,
You will not find extractor 2LIS_03_BX in t/code LBWE. It's a special extractor used to initialize stocks and cannot be customized and neither be configured in any way. It does not have added value to show it here.
Please refer to the document Re-initialization of the Material Stocks/Movements cube (0IC_C03) with 2LIS_03_BF, 2LIS_03_BX and 2LIS_03_UM in BW 7.x for more information and a step-by-step guide how to execute such a process.
Last but not least, you will have to activate DataSource 2LIS_03_BX using t/code RSA5 like any other Business Content DataSource and as already suggested by Raman.
Best regards,
Sander