If you are working in z/OS UNIX System Services, give each user a separate mountable file system to avoid I/O contention.
If the compiler is not in LPA, tune your jobs to avoid channel and pack contention when the headers and the compiler are on the same pack and multiple compile jobs are executing.
FILESYSTYPE TYPE(TFS) ENTRYPOINT(BPXTFS)
This is described in more detail in z/OS UNIX System Services Planning.