Basically, if you are on Oracle 11g, you need to be on version 22.214.171.124.0
All lower versions are currently unsupported.
If you are on 126.96.36.199.0 Premier Support (aka regular support) is no longer available. For support at this point, you would need to purchase "Extended Support". However, to make this even more complicated, Oracle has waived costs for Extended Support for all customers with a valid support contract until December 31, 2018.
Basically, what this means is that customers will have support for version 188.8.131.52.0 until the 2018.12.31 above at no cost.
However, at this point, all users start need to start looking at upgrading to 12c. At the very least you need to set a test instance to start testing all your processes.
Keep in mind that in addition to the database objects, all forms, C and COBOL need to be recompiled for this upgrade.
Both Oracle 12c versions 12.2.x and 12.1.x support Banner®.
For more information check the Oracle Support FAQ here.
In addition, click here for an FAQ on installing Oracle 12c in Unix/Linux environments.