The first time you share Rational Developer for System z resources to a repository workspace in Rational Team Concert, or load Rational Team Concert resources from a repository workspace into MVS subprojects, you must associate a build context with the repository workspace.
A build context is a collection of metadata from a build definition. You can specify additional properties for the build context the first time you share or load to a specific repository workspace. The association between the repository workspace and a build context remain as long as there are shared artifacts present in the local eclipse workspace. The build context describes how artifacts associated with the repository workspace should be built.
The data set prefix and variable substitution values defined in the build context establish the characteristics of your z/OS® sandbox. Source-controlled files are extracted to your z/OS sandbox and then built from your z/OS sandbox. Once a build context is associated with a repository workspace, all future share or load operations involving the same repository workspace must use that build context, unless all MVS subproject members that are associated with the zFiles in a repository workspace have been disconnected.
For detailed examples of the setup required before you share or load zFiles, see Tutorial: Using an Ant with enterprise extensions build to compile a COBOL application.