Dear Sandeep,
Encashment of leave pertains only to PL/EL/Annual Leave with Wages as the nomenclature used in the establishment -specific law. The statutory compliance for encashment arises only on one occasions viz., termination of employment of the employee.
Encashment of leave on any such ground,therefore, is a statutory alternative for its enjoyment. As such the value of surrender leave shall be computed on the basis of gross salary only.In this regard I would suggest that one can draw an analogy from the provisions of sec.80 of the Factories Act,1948 relating to wages during leave period.