Yogesh, I am also new to the F&O game but will try to answer your query to the best of my knowledge.
It is not compulsory or obligatory to give a stop-loss in any deal. You can find it even in cash (delivery) purchase screens. However, it is a good safeguard if you do a lot of trades and cannot devote attention to the price variations of individual scrips during the day or if you are having some other employment and cannot monitor the price movement during the day. In such cases, the stop-loss is a useful tool as it initiates a sell action automatically in case of a buy order or vice versa in case of a sell order and thus minimises your loss if the price were to move too far in the direction negative to what you intended.
It however has the disadvantage in the volatile and unpredictable market today in that often the price moves in the direction opposite to what you expected on opening and your stop-loss gets activated and then the market reverses direction and reaches or surpasses your expected target later. This has happened to me on several occasions and left me almost tearing my hair off in frustration.
The best thing to do would be to manually monitor the market and price movements on a TV and your computer monitor simultaneously and either keep moving the stop-loss manually depending on the price movement on either direction as appropriate. This will not only prevent undue loss but also safeguard any profit that might already have accrued.
As far as ICICI is concerned, it is generally worthless to keep a stop-loss. I have found that the stop-loss does not work many times, especially if the market moves too fast (like it happened after the P-note issue and on 17th December). Also, ICICI gives too many idiotic and illogical hurdles for giving a stop-loss. (For example, when I place a buy order for a futures at 300 rupees, if I place a stop-loss at 295, it throws a message saying that the stop-loss cannot be less than the limit price. If I place a sell order for 300 and a stop-loss of 305, it says stop-loss cannot be more than the limit price.) Stupid, but we have to put up with it.
One important to keep in mind with ICICI is that you automatically get logged off if there is no activity in your browsing for more than a minute or so. So you need to keep changing the menu options randomly or keep the Open Positions page of the futures section open and keep refreshing your browser every minute, in case you are a day trader or have access to the online account at office.
