Explanation
 The file is not in use but has not timed out yet (occurs most
often when writing to PDS or PDSE members without writetimeout expiring
between saving members).
The file is in use by a z/OS user or another client.
Dynamic allocation–authorized function requested by an unauthorized
user.  The error codes from dynamic allocation are printed to the
log data set.
The Resource Access Control Facility (RACF) is not active.
Dynamic allocation–The request was denied by the operator (dsname
allocation).  The error codes from dynamic allocation are printed
to the log data set.
Dynamic allocation–The installation validation routine denied
this request. The error codes from dynamic allocation are printed
to the log data set.
You are not authorized for this request.
The system operator suspended mount request processing (only if
this message appears following a mount attempt).
The file/prefix is not exported to the client (only if this message
appears following a mount attempt).
IDCAMS failed during a rename or remove procedure. Usually this
happens because the file is in use. The output from IDCAMS is printed
to the log data set.
With OS/2, you might get a "SYS0055  Access denied" message
if the noretrieve attribute is set and a dir command
is done against a mounted file system containing migrated files.

User response
 For explanation 1, to determine if this is the
problem, check the timeout values (attrtimeout, readtimeout, writetimeout).
Retry the request after the shortest timeout expires. If the request
still fails, retry the request after the next shortest timeout expires.
 If the request still fails, retry after the longest timeout expires.
 If the request still fails, this is not the problem.
 For explanations
2 and 10, retry the request later.
 For explanations 3, 4, 5,
6, and 9, notify the system programmer.
 For explanation 7,
enter the mvslogin command again and retry the request. If
the request still fails, notify your system programmer.
 For
explanation 8, notify your system operator or system programmer.
 For
explanation 11, specify the retrieve attribute in the mount command,
or the system administrator can make that the default.