These files are language specific, and are goverend by the APS_LANG_LOGS environment variable. APS writes to these datestamped log files when it cannot find proper translations in the appropriate APS.lang file.
To set this once, modify the the nete_ps_env.ksh script, so that when you source the file, you will pick up the new environment variable. An example of setting this would be to add:
APS_LANG_LOGS="/your/new/path"; export APS_LANG_LOGS
You should add this towards the top of the file.
More information can be found in the APS Admin Guide on page 420:
The library may need to write log information. If so, it will create a log file named using the current date in the format YYYYMMDD.log.
These log files will be placed in a subdirectory under the language directory (see above) called "logs", if the subdirectory already exists.
If it does not already exist, the files will be placed in the language directory itself.
You can also specify the directory into which the logs are to be placed using an environment variable called APS_LANG_LOGS. Note that wherever the files are to be placed, the current user must be able to create and write to this directory.
If the directory does not exist or is not writable, no logs will be written.