MAPSET exists with this name.
Explanation
From an in-memory control block perspective, CICS
treats PROGRAM, MAPSET and PARTITIONSET
definitions "equally". Therefore, it is strongly
desirable to have the NAME attribute value in
this set of definition types to be globally
unique. If the NAME attribute is not unique in
this set of Resource Types, CICS may replace a
definition of one Type with another of a
different Type. This may, or may not, have an
undesirable outcome.
System action
The flagged definition is reported as "not
installable".
User response
Examine all MAPSET, PARTITIONSET and PROGRAM
definitions having duplicate NAME attribute
values and either make them unique or remove them
from the Group (Candidate) List.