Procedure steps

The information in this topic is taken from the following VTAM® storage diagnosis information APARs:

II06752: An Introduction/Overview
II04548: Documentation Requirements
II07563: Private Storage Problems
II07564: CSA Storage Problems

Check for common CSA and private storage messages.

Use the following messages to determine if the storage shortage is occurring in CSA or private storage. If the message is issued frequently or continuously, this indicates that a dump is needed to provide additional information.

Table 1 lists the messages that are associated with CSA storage problems.

Table 1. IST messages associated with CSA storage problems
Message number	Description
IST154I	Indicates that expansion failed for one of the fixed-length buffer pools in ECSA subpool 231. The error code displayed in the message provides additional information.
IST561I	Indicates that SLOWPT has occurred in one of the fixed-length buffer pools in ECSA subpool 231. If this message occurs only occasionally, you might need to do some tuning in this area. If the console is flooded with this message, you might have a CSA problem.
IST562I	Indicates that a storage request has failed because of one of the following reasons: CSALIMIT start option or MODIFY CSALIMIT is not specified and total CSA plus ECSA allocations have reached 90% of the total CSA plus ECSA defined in the system. CSALIMIT start option or MODIFY CSALIMIT is specified and total CSA plus ECSA allocations have reached 75% of the total amount of CSA plus ECSA defined in the system. CSALIMIT start option or MODIFY CSALIMIT is specified with the ,F command modifier and the total CSA plus ECSA VTAM usage has reached this value.
IST564I	Indicates that a GETMAIN failed for the CSA subpool specified in the message. The specified subpool might be the sources of the CSA problem or the problem might be caused by another CSA subpool that is affecting the subpool displayed in the message. Further investigation into the contents of storage is required.
IST1832I	Indicates that the value coded on the CSALIMIT start option or a MODIFY CSALIMIT command is less than 25 megabytes, which may be too small. This might result in IST562I messages (only if the ,F command modifier is specified). Use the DISPLAY BFRUSE command output to monitor CSA usage and modify the CSALIMIT value if maximum CSA usage approaches the CSALIMIT value (this is necessary only if the ,F command modifier is specified).
IST1833I	This message will be issued only if the CSALIMIT start option or MODIFY CSALIMIT command is issued without the ,F modifier. Issue a DISPLAY BFRUSE,SUMMARY=* command and compare the MAXIMUM value in the first IST449I message to the value in IST1667I. If the first value is close to 75% of the second value, it means that VTAM is using a large proportion of system CSA storage. If so, an analysis of VTAM's storage use is indicated. If VTAM is not a large user of system storage but message IST1831I indicates close to only 25% of system CSA plus ECSA storage remains available for use, allocation of additional CSA or ECSA storage, or both, may be needed. A determination of which process is potentially using an inordinate amount of CSA or ECSA storage, or both, may also be needed.

See the description of the message in z/OS Communications Server: SNA Messages for additional information.

Table 2 lists the messages that are associated with private storage problems. See the description of the message in z/OS Communications Server: SNA Messages for additional information.

Table 2. IST messages associated with private storage problems
Message number	Description
IST563I	Indicates that the MAXPVT value has been reached. This value specifies how much private area subpool 229 storage VTAM can use within the address space of the application program displayed in the message. This indicates a problem with the application, not a VTAM problem.
IST565I	Indicates that a GETMAIN failed for the VTAM private area subpool displayed in the message. The specified subpool might be the source of the problem or the problem might be caused by another subpool that is affecting the subpool displayed in the message. Further investigation into the contents of storage will be required.
IST566I	This message is the same as IST563I except that MAXPVT was not specified on the APPL definition statement. This message does not indicate a VTAM problem.

Request a full dump.
If storage-related messages are issued frequently or continuously, dump VTAM common and private storage areas. The dump can help you determine the location of the storage problem.
- See Formatting and printing dump output for information on the VTAM interactive problem control system (IPCS).
- Several storage-related dump analysis tools are available. See STORAGE, VTAM, and VTBUF for descriptions of these tools.
- If external trace is active, see Analyzing storage for information about analyzing storage using the VIT analysis tool. see information on internal and external trace recording in z/OS Communications Server: SNA Diagnosis Vol 2, FFST Dumps and the VIT for additional information.
Note:
1. The best dump for diagnosing VTAM storage problems is a full dump.
  If the dump is partial, examine the reason text of MVS™ message IEA911E to correct the problem so that you can obtain a full dump. The most common reason for a partial dump is that the dump data set is not large enough. In this situation, calculate the DASD space requirements and reallocate the dump data set.
  
  For a complete description of the required documentation for storage problems, see information APAR II04548.
2. Although VTAM detects storage shortages in the common storage area, VTAM might not be causing the shortage because this area is shared by all address spaces.
Use IBMLink to find additional problem determination information.
If you have access to IBMLink, take the following actions:
- Review the appropriate VTAM storage diagnosis information APARs. See Procedure steps for a list of these APARs.
- Use your error messages and dump to determine key words for searching IBMLink for additional information and known problems.
If you do not have access to IBMLink and need additional assistance, go to step 4.
If you need additional assistance, contact the IBM® support center at 1-800-IBM-SERV.