In the documentation Common Services for z/OS 15.0 in the chapter :
Deploy and Configure CCS Apache Tomcat, this step describes :
A product might deliver a WAR file in its installation. Use the following JCL to copy the WAR file into the CCS Apache Tomcat instance.
What is a WAR file?
What is the meaning for those kind of files ?
Common Services 14.1 & 15.0 - z/OS supported releases -
A WAR file (Web Application Resource or Web application archive) is a file used to distribute a collection of JAR-files, JavaServer Pages, Java Servlets, Java classes, XML files, tag libraries, static web pages (HTML and related files) and other resources that together constitute a web application.
Reference the IBM documentation for the definition and details of a WAR file