Calculating the size of your page sets

For queue manager object definitions (for example, queues and processes), it is simple to calculate the storage requirement because these objects are of fixed size and are permanent. For messages however, the calculation is more complex for the following reasons:

• Messages vary in size.

• Messages are transitory.

• Space occupied by messages that have been retrieved is reclaimed periodically by an asynchronous process.

Large page sets of greater than 4GB that provide extra capacity for messages if the network stops, can be created if required. It is not possible to modify the existing page sets. Instead, new page sets with extended addressability and extended format attributes, must be created. The new page sets must be the same physical size as the old ones, and the old page sets must then be copied to the new ones. If backward migration is required, page set zero must not be changed. If page sets less than 4GB are adequate, no action is needed.