ABCs of z/OS System Programming Volume 3 - IBM Redbooks

2. Define or alter your existing catalogs with the attribute ECSHARING using the IDCAMS
DEFINE or ALTER commands.
The ECSHARING attribute makes a catalog eligible for sharing using the ECS protocol,
as opposed to the VVDS/VVR protocol. The catalog can still be used in VVDS mode.
3. Activate all eligible catalogs for ECS sharing.
You can use the command MODIFY CATALOG,ECSHR(AUTOADD) on one system to activate all
ECS-eligible catalogs throughout the sysplex for ECS sharing. They are automatically
activated at their next reference. You can manually add a catalog to use ECS by running
the command MODIFY CATALOG,ECSHR(ENABLE,catname) where catname is the name of the
catalog you want to add.
Only catalogs that were added are shared in ECS mode. The command MODIFY
CATALOG,ECSHR(STATUS) shows you the ECS status for each catalog, as well as whether it is
eligible and already activated.
Restrictions for ECS mode usage
The following restrictions apply to ECS mode usage:
► You cannot use ECS mode from one system and VVDS mode from another system
simultaneously to share a catalog. You will get an error message if you try this.
Important: If you attempt to use a catalog that is currently ECS-active from a system
outside the sysplex, the request might break the catalog.
► No more than 1024 catalogs can currently be shared using ECS from a single system.
► All systems sharing the catalog in ECS mode must have connectivity to the same
Coupling Facility, and must be in the same global resource serialization (GRS) complex.
► When you use catalogs in ECS mode, convert the resource SYSIGGV2 to a SYSTEMS
enqueue. Otherwise, the catalogs in ECS mode will be damaged.
For more information about ECS, see z/OS DFSMS: Managing Catalogs, SC26-7409. For
information about defining Coupling Facility structures, see z/OS MVS Setting Up a Sysplex,
SA22-7625.
376 ABCs of z/OS System Programming Volume 3