While ordinary system files such as SYSDTA, SYSOUT and SYSLST merely transfer sequences of data records, where each data record corresponds to a text string, S variable streams transfer entire variable structures. The TRANSMIT-BY-STREAM command transfers such a structure to the stream; the stream must already be assigned to a suitable server that will accept the structure, process it and acknowledge it with return information.
FHS is available for use as such a server. FHS can output the structure contents to the terminal and return user input via predefined screen masks. A detailed description of “FHS as output server” is given in section “FHS as output server”.
A variable can in turn be used as a server that accepts the structures transferred via a stream for further analysis.
While output from a single command can be directed to a variable by means of the EXECUTE-CMD command, the predefined system streams SYSINF, SYSMSG and SYSVAR continually receive structured command and message outputs for various commands.