Default trace file name is $HOME/.als/traces.cfg.
You can provide another file by --tracefile=<FILE> command line option.
Here is a list of supported settings.
Show all the server input. Use this way:
ALS.IN=yes > inout.txt:buffer_size=0
Show all the server output. Use this way:
ALS.OUT=yes > inout.txt:buffer_size=0
Trace requests, notifications and responses in an ALS log file.
ALS.MAIN=yes
Request incremental (if yes) or full content (if no)
text document syncronization
in initialize response.
ALS.ALLOW_INCREMENTAL_TEXT_CHANGES=no
Log lalpp output if yes.
ALS.LAL_PP_OUTPUT_ON_FORMATTING=yes