The question is a little vague, a database default tablespace maybe 1 GB in size. This does not include any redo log files and any other files required to support the Oracle instance on the file system. Also, the default tablespace USER and TEMP are avoided since our doc suggest that each CLM user (schemas) own their default and temp tablespaces.
Looking at the scripts to create the CLM solution, the 1 GB initial size becomes irrelevant. The Tool by default will required close to 5 GB of Disk space.
PLease review the following two links
More Control over the DB2 Data Warehouse Setup
https://jazz.net/wiki/bin/view/Main/MoreControlOverTheOracleDataWarehouseSetup
The Total size for the DW becomes 1.2GB.
The recommended scripts for each of the product recommend to start the Tablespace size to 1 GB each.
Setting up an Oracle database
http://pic.dhe.ibm.com/infocenter/clmhelp/v4r0m6/topic/com.ibm.jazz.install.doc/topics/t_s_server_installation_setup_oracle.html