You can increase your page file size, or let Windows manage it. You can also turn down the amount of RAM used by other system resources in the BIOS.
To make sure your Page File is set to optimal settings:
Open the Control Panel and go to System Properties. On the Advanced tab, in the Performance section, click the Settings button. In the Performance Options dialog, select the Advanced tab and in the Virtual Memory section click the Change button. In the Virtual Memory dialog, is the Paging File Size set to System Managed? If so, that should be best. If you want, though, you could set a custom size based on the application needs.
To free up more memory from other hardware resources:
Open your BIOS settings by rebooting your computer and following the instructions on the POST screen. If you have integrated graphics, turn down the amount of memory assigned to graphics to the lowest possible setting.
If these do not work, your application is either not capable of running on a system with only 3GB RAM, or when it refers to User Space it is not talking about RAM. In this case check your HDD to see if it is running out of space and use a program such as CCleaner (by Piriform) to free up space on your HDD.