ALCS, which stands for Airline Control System, is an application server that provides industrial-strength, online transaction management for mission-critical applications. ALCS is a transaction processing monitor for the IBM System/360, System/370, ESA/390, and zSeries mainframes. It is a variant of TPF specially designed to provide all the benefits of TPF (very high speed, high volume, and high availability in transaction processing) but with the advantages such as easier integration into the data center offered by running on a standard IBM operating system platform.