The confSTDIR macro defines the location (directory) where the sendmail program's statistics file will be found (see Section 5.4.1 for a description of this file). The confSTDIR macro assigns its value to the STDIR Makefile directive. It is very unlikely that you will ever have to change this from the value that is predefined for you in your devtools/OS file. But one reason to relocate this file would be the need to locate it on a read/write disk, where /etc/mail is mounted read-only:

define(`confSTDIR', `/var/run/statistics')

Note that, if you redefine this directory, you must also redefine the STATUS_FILE configuration macro (Section 5.4.1) so that the correct path appears in your sendmail.cf file's StatusFile option.

Also note that -E DESTDIR (See this section) can be used to relocate all installation directories.