Here is what you looking for:
- Minimum Heap Size – the minimum size of the JVM memory allocation pool, in megabytes. Sybase recommends that this value not fall 500 megabytes for a 32-bit operating system, but 1 gigabyte is recommended. For a 64-bit operating system, Sybase recommends 1 gigabyte for a normal configuration, but 2 gigabyte for a stress configuration (which can vary depending on what RAM is available).
- Maximum Heap Size – the maximum size of the JVM memory allocation pool, in megabytes. For a 32-bit operating system, Sybase recommends a 1.5 gigabyte maximum heap size value. For a 64-bit operating system, Sybase recommends 1 gigabyte for a normal configuration, but 4 gigabyte for a stress configuration (which can vary depending on what RAM is available).