There is an explanation of Avalkredite on this website: http://www.wirtschaftslexikon24.com/d/avalkredit/avalkredit....
The credit facility is the amount which can be drawn on. It can also be called "guaranteed credit facility" but that sounds as if the credit amount is guaranteed rather than it being covered.

"A counter guarantee is a guarantee given by the surety to the principal debtor providing him with continuing indemnity against the loss or damage that the surety may suffer on account of default on the part of the principal debtor." (wiki answers)
"A counter guarantee is a back-to-back guarantee given by an obligor to indemnify a surety in a three-party contract (such as a performance bond). A counter guarantee is cashed in the unexpected event the obligor fails in the performance of a contract and the obligee calls upon the surety to honor the bond (guaranteed by the surety on behalf of the obligor). http://www.businessdictionary.com/definition/counter-guarant...

In short, if A does not give notice for termination of the guarantee credit before 2 years of its expiry, then it gets automatically exteded.

So, the second Zusage mentioned is actually not a commiment, but a condition in tetms of the agreement.