As of Sep 30 2016, z/OS V1.13 support ends. What this means is, if you ran into issues using this release you will not get help from IBM. Your option is to move to latest release of z/OS.
There are 2 types of support life cycles policies.
3+2 support policy: This is called standard support. A minimum of 3 years of support from the date of product release plus an option to get support extension for 2 more years from End Of Support (EOS) with a fee. As an example, z/OS V1.13 was released on Sep 30 2011. With 3+2 support policy you will get technical support till Sep 30 2016.
5+3 support policy: This is called Enhanced support. A minimum of 5 years of support from the date of product release plus an option to get support extension for 3 more years from End Of Support (EOS) with a fee. IBM aggressively shifting products to this support policy.
There is one other aspect you need to be aware of support life cycle policies. i.e N-2 support. IBM has undertaken a new initiative whereby IBM will, provide support for the current version of select products plus the two previous versions (N-2). The N-2 initiative only applies to select IBM branded products that were still being supported and had not announced EOS as of August 1, 2011
For more details, use below links: