Visa and MasterCard combined trading standards under the umbrella of the Payment Card Industry Data Security Standard (PCIDSS) Mainframes cannot encrypt data which is one of the compliance measures required under the new standard. Visas head of third-party assurance, Edward Lodens, said in the mainframe world, the process of encrypting data is very difficult, even though associated costs are falling. National Australia Bank spokesman said the organization will certainly be sticking with mainframes in the foreseeable future.”]
Source: https://www.csoonline.com/article/2119040/mainframe-users-struggle-with-new-compliance-measures.html