Chandan, It isn't mandatory to secure a good job with just 60% marks in Class XII. But many well known entrance examinations in India require atleast 60% in 12th as a eligibility criteria. Actually It depends the company recruiting and their criteria. Some are strict with their criteria whereas some focus on all aspects of a student. Do not worry, secure good marks in your engineering and you 12th marks will hold less weightage.
It is good to score 60% in the examination of class 12 as it will act as a catalyst to get a job or to set up a career. But government jobs require studious people for their organizations so that the future employees could able to handle any situations in case of urgency of the government and honesty as well as sincerity is the foremost aspect for a good job.
60% out of 100% considered as first division. To appear in any competitive exam the basic requirements or criteria is 60% in class 10th 12th and in graduation also its an standard criteria it may vary according to exam and certain condition so for a secure site it always preferable to be with 60% and more.
For govt. job the 60% is not necessary but if you want job in engineering field then there you can face problem with this, there some company maintain there criteria for job 10th, 12th minimum 60%.