# Configure Transformer's JVM

Transformer includes an embedded Java virtual machine (JVM). The JVM is deactivated by default.

## Activating the JVM

Transformer and other C-based DataSource applications do not load an embedded JVM by default. To load an embedded JVM, set the value of [`jvm_location`](../datasource/datasource-java-jvm-configuration.md#jvm-location) to the value of the Caplin Deployment Framework’s `JVM_LOCATION` macro.

Feature blades and Transformer modules that require a JVM include a configuration override file, `java.conf`, that sets the value of [`jvm_location`](../datasource/datasource-java-jvm-configuration.md#jvm-location):

```
jvm_location = {$JVM_LOCATION}
```

**📌 NOTE**\
The Persistence Service configuration blade for Transformer 7 includes a `java.conf` file with a `jvm_location` override, but the `jvm_location` line is commented out by default. If you require database-backed persistence (required in production environments), you must uncomment this line. For more information, see [Activating the Persistence Service 7](transformer-activating-the-persistence-service-7.md).

## Configuring the JVM

Transformer uses the standard JVM configuration options for C-based DataSource applicatons. See [Java (JVM) Configuration](../datasource/datasource-java-jvm-configuration.md).

For more detailed instructions on changing the size of the JVM’s heap, see [Change the size of the JVM heap](../datasource/datasource-change-the-size-of-the-jvm-heap.md).