public void setCallStack(CallStack stack) {
        DocprocExecutor ex = ((getExecutor() == null) ? new DocprocExecutor(getName(), stack) : new DocprocExecutor(getExecutor(), stack));
        setExecutor(ex);
    }
Sets a new processing stack for this service. This will be the Prototype
for the call stacks of individual processings in this service
docproc/src/main/java/com/yahoo/docproc/impl/DocprocService.java