Limiting Logon Attempts and Predefining Clients 
You can use the following system profile parameters to limit the permitted number of failed logon attempts and to set the default client.
Default: 3. You can set it to any value between 1 and 99.
Default: 12. You can set it to any value between 1 and 99.
You maintain the system profile parameters by choosing Tools
® CCMS, Configuration ® Profile maintenance.To make the parameters globally effective in an R/3 System, set them in the default system profile DEFAULT.PFL. However, to make them instance-specific, you must set them in the profiles of each application server in your R/3 System.