The Job Scheduler is a 32-bit engine but you can run it on any of the supported 64-bit platforms.
The Job Scheduler requires a Sun Java Runtime Environment (JRE) 32-bit in version 1.6.x or newer.
On AIX systems you can also use the IBM Java 32 bit in version 1.6.x.
You can install the 32-bit Java in parallel to a 64-bit version.
See "Z-JAVA-101 Java Virtual Machine is not started" for more information if you have the wrong JRE.
On 64-bit Ubuntu systems it is possible that you get the message "/bin/sh: ./bin/scheduler: not found". If this happens see this FAQ.