Enabling a Catalog for ECS Mode

A new attribute, ECSHARING, is available on the IDCAMS DEFINE and ALTER commands. Setting this attribute will make a catalog eligible for sharing using the ECS protocol, as opposed to the VVDS protocol. However, the system will not actually use the ECS protocol unless:

There is an active connection to the ECS cache structure AND
The ECS mode has been activated by the MODIFY CATALOG, ECSHR(AUTOADD) command.

You can alter the ECSHARING attribute of a catalog at any time. If you remove the attribute and the catalog is currently using ECS mode, it will be converted back to VVDS mode on all systems that are sharing it. This is convenient if you find that the catalog must be accessed by a system that does not support the ECS protocol. A catalog cannot be shared using both the ECS and VVDS protocols at the same time. Therefore, it is necessary to stop ECS mode for a catalog if access is needed by a system that does not support the ECS protocol. This can be temporarily accomplished by using the MODIFY CATALOG ECSHR(REMOVE,catname) command. This does not remove the ECSHARING attribute, but does remove the catalog from ECS mode on all systems. It can only be returned to ECS mode by issuing a MODIFY CATALOG ECSHR(ENABLE,catname) command.