The GÉANT SIG-CISS (Cloudy Interoperable Software Stacks) is proposed to be the successor of the long running TF-Storage task force of GÉANT with a wider scope extending from data storage to general cloud infrastructure software stacks, platforms and research workflows. The SIG brings together those who are building/operating R&E clouds and are willing to share strategy, design, deployment, performance optimization, application integration, interoperability, security and other related information, knowledge and best practices as well as participate in joint efforts aimed at addressing needs of academic environment related to building, operating, brokering cloud services and infrastructure and ensuring their interoperability.