Transport classes are defined independently for each system in the sysplex using the CLASS keyword of the CLASSDEF statement or, after IPL, using the SETXCF START,CLASSDEF command. Figure 1shows the syntax of the statement.

[CLASSDEF                                            ]
[           CLASS(class-name)                        ]
[          [CLASSLEN(class-length)           ]       ]
[          [GROUP(group-name[,group-name]...)]       ]
[          [MAXMSG(max-messages)             ]       ]

On a system, each transport class must have a unique name. The class name is used in system commands and shown in display output and reports.

For some applications, the same transport class definition is suitable for all systems in the sysplex. For example, an application, such as global resource serialization, whose members in the SYSGRS XCF group on the various systems in the sysplex operate in a peer relationship, has similar message traffic patterns on all systems. In this case, defining the same transport class (such as TCGRS) on each system simplifies the task of reviewing measurement reports for the sysplex.