Understanding Hiring Freezes in Large Companies
In big companies, hiring is based on anticipated business. However, if the business doesn't come through and they already have enough people on the bench (awaiting placement on new projects), they impose a 'hiring freeze' as a business necessity. You may find yourself in that situation. The only sensible solution is to join another company and develop your experience profile.
Advice for Freshers
My advice to freshers is not to be content with a verbal assurance from any company that you have been selected. Unless you receive an offer letter, it is fair to assume that you have no job in hand. Also, remember that having an offer letter does not guarantee a job until you receive your 'Appointment Letter' and accept its terms and conditions. Your employment becomes effective from the date you join an organization.
So, there's no point in boasting that IBM has selected you and you are awaiting their offer. No other employer will value such claims; you have to prove your worth through their selection process. Instead of living on false hopes, join a company (big or small) that provides you with an appointment letter. Give your best, prove your worth, and aim for continuity in the same organization for a minimum of 2-3 years. After that, if necessary, seek different experiences. Your primary goal in the initial years should be to learn more (not earn more) and acquire expertise that naturally fuels your growth.
If you can benefit from this free advice, you can consider yourself a mature person.