hide random home http://www.fmi.uni-passau.de/archive/doc/unix/unixhelp/Unixhelp/shell_ksh_hist1.html (Einblicke ins Internet, 10/1995)
Changing the size ofthe command history

Changing the size ofthe command history

By default the previous 128 commands are saved in the command history list.

or larger number of commands. For example: 
   HISTSIZE=50;export HISTSIZE

This will keep a history of the fifty (50) most recent commands that you have used.