The cross memory local lock (CML) is provided to allow cross memory services to serialize resources in an address space that might not be the home address space. It has the same attributes as the LOCAL lock. (The LOCAL lock refers only to the home address space pointed to by PSAAOLD.) The owner of a CML lock can be suspended for the same reasons as the owner of the LOCAL lock, such as CMS lock suspension or page fault suspension.
In a multi-tasking environment, it is possible for more than one task or SRB in an address space to obtain a local level lock. For example, task A might own the LOCAL lock of its address space while task B in the same address space owns the CML lock of address space C.
To prevent possible system deadlocks, only one lock at the local level can be held at one time by a unit of work. If a CML lock is requested while owning the LOCAL lock, the requestor will be abended. The same is true if the LOCAL lock is requested while owning a CML lock.
Either a CML lock or the LOCAL lock must be held to request the cross memory services lock (CMS).
The requestor of a CML lock must have authority to access the specified address space prior to the lock request. This is accomplished by setting the primary or secondary address space to that specified on the lock request. The specified address space must be non-swappable prior to the obtain request.