May be below statements from prhelp will help

Changing the default keystore caching settings

You can change the values of the KeyStoreCacheExpireTime and KeyStoreCacheSize settings to control how often the keystore cache is refreshed and restrict cache size. The lower the values, the less memory is used, but processing power is reduced.

When you create a Keystore data instance, you select the reference, from which the keystore entries are sourced.

• If you choose Reference to file or Reference to URL, Pega Platform caches the keystore entries for the time set in the Cache keystore field.
• If you choose Upload file, Pega Platform caches the keystore entries for the time set in the KeyStoreCacheExpireTime Dynamic System Setting.
• If you select Reference to data page, Pega Platform caches the keystore entries for the time set in the KeyStoreCacheExpireTime Dynamic System Setting, provided that you do not populate the Load Management tab,Refresh strategy area.

To change the values of the KeyStoreCacheExpireTime and KeyStoreCacheSize settings, do the following steps.

1. In the Designer Studio search field, enter the name of the Dynamic System Setting that you want to modify and press Enter.
2. In the list of results, click the Dynamic System Setting that you want to modify:

   • KeyStoreCacheExpireTime - Stores the default caching time of the keystore entries (in seconds). The default value is 3600.

   • KeyStoreCacheSize - Stores the number of keystore entries that can be held in cache. The default value is 150. It is recommended to set the value to no less than 50.

3. Change the value in the Value field.
4. Click Save.
5. Repeat steps 1 thru 4 for each Dynamic System Setting that you want to modify.