Dear PRJS,
The term 'mandatory' means "something required by law". Leave in general to the persons employed is a statutory welfare measure or a particular condition of employment finding place in the contract of employment which gets reflected in the service regulations applicable as the case be. Therefore, one can give you a correct answer only when it is known what kind of industrial establishment that " every Pvt LTD Company" you mentioned is. You can find mandatory leave provisions only in establishment-specific labor laws like the Factories Act,1948, the Plantations Labor Act,1951, State Shops and Establishments Acts etc., differing in types of leave and their scales depending on the nature of activities. So it is essential that your query indicates the type of the establishment.
It is discernible from the replies that some of the learned members have used the terms "leave" and "holiday" interchangeably. Sorry they cannot be one and the same in the Indian legal context. "Leave" means "leave of absence from work or the place of work". They may be of different types like casual leave, sick leave, earned or privilege leave as provided for in the applicable establishment-specific labor law. Therefore, the automatic implication is that though mandatory, leave cannot be claimed by an employee as a matter of right and the employer has the discretion to sanction it or refuse it depending on the exigencies of work. Thus leave is an authorised absence with or even without wages/salary. On the other hand, holiday is the authorised absence with wages/salary on certain predetermined occasions which requires mostly no prior sanction of the employer.