Broker Resource Allocation

The EntireX Broker is a multithreaded application and communicates among multiple tasks in memory pools. If you do not need to restrict the memory expansion of EntireX Broker, we strongly recommend you enable the dynamic memory management in order to handle changing workload appropriately. See Dynamic Memory Management under Broker Resource Allocation below. If dynamic memory management is disabled, non-expandable memory is allocated during startup to store all internal control blocks and the contents of messages.

This document covers the following topics:


General Considerations

Resource considerations apply to both the global and service-specific levels:

  • Dynamic assignment of global resources to services that need them prevents the return of a "Resource Shortage" code to an application when resources are available globally. It also enables the EntireX Broker to run with fewer total resources, although it does not guarantee the availability of a specific set of resources for a particular service.

  • Flow control ensures that individual services do not influence the behavior of other services by accident, error, or simply overload. This means that you can restrict the resource consumption of particular services in order to shield the other services.

In order to satisfy both global and service-specific requirements, the EntireX Broker allows you to allocate resources for each individual service or define global resources which are then allocated dynamically to any service that needs them.

The resources in question are the number of conversations, number of servers, plus units of work and the message storage, separated in a long buffer of 4096 bytes and short buffer of 256 bytes. These resources are typically the bottleneck in a system, especially when you consider that non-conversational communication is treated as the special case of "conversations with a single message only" within the EntireX Broker.

Global resources are defined by the parameters in the Broker section of the attribute file. The number of conversations allocated to each service is defined in the service-specific section of the attribute file. Because the conversations are shared by all servers that provide the service, a larger number of conversations should be allocated to services that are provided by more than one server. The number of conversations required is also affected by the number of clients accessing the service in parallel.

Specifying Global Resources

You can specify a set of global resources with no restrictions on which service allocates the resources:

  • Specify the global attributes with the desired values.

  • Do not specify any additional restrictions. That is, do not provide values for the following Broker-specific attributes:

    LONG-BUFFER-DEFAULT
    SHORT-BUFFER-DEFAULT
    CONV-DEFAULT
    SERVER-DEFAULT

  • Also, do not provide values for the following server-specific attributes:

    LONG-BUFFER-LIMIT
    SERVER-LIMIT
    SHORT-BUFFER-LIMIT
    CONV-LIMIT

Example

The following example defines global resources. If no additional definitions are specified, resources are allocated and assigned to any server that needs them.

NUM-CONVERSATION=1000
NUM-LONG-BUFFER=200
NUM-SHORT-BUFFER=2000
NUM-SERVER=100

Restricting the Resources of Particular Services

You can restrict resource allocation for particular services in advance:

  • Use CONV-LIMIT to limit the resource consumption for a specific service.

  • Use CONV-DEFAULT to provide a default limit for services for which CONV-LIMIT is not defined.

Example

In the following example, attributes are used to restrict resource allocation:

DEFAULTS=BROKER
NUM-CONVERSATION=1000
CONV-DEFAULT=200

DEFAULTS=SERVICE
CLASS=A, SERVER=A, SERVICE=A, CONV-LIMIT=100
CLASS=B, SERVER=B, SERVICE=B, CONV-LIMIT=UNLIM
CLASS=C, SERVER=C, SERVICE=C
  • Memory for a total of 1000 conversations is allocated (NUM-CONVERSATION=1000).

  • Service A (CLASS A,SERVER A,SERVICE A) is limited to 100 conversation control blocks used simultaneously (CONV-LIMIT=100). The application that wants to start more conversations than specified by the limit policy will receive a "Resource shortage" return code. This return code should result in a retry of the desired operation a little later, when the resource situation may have changed.

  • Service B (CLASS B,SERVER B,SERVICE B) is allowed to try to allocate as many resources as necessary, provided the resources are available and not occupied by other services. The number of conversations that may be used by this service is unlimited (CONV-LIMIT=UNLIM).

  • Service C (CLASS C,SERVER C,SERVICE C) has no explicit value for the CONV-LIMIT attribute. The number of conversation control blocks that it is allowed to use is therefore limited to the default value which is defined by the CONV-DEFAULT Broker attribute.

The same scheme applies to the allocation of message buffers and servers:

  • In the following example, long message buffers are allocated using the keywords NUM-LONG-BUFFER, LONG-BUFFER-DEFAULT and LONG-BUFFER-LIMIT:

    DEFAULTS=BROKER
    NUM-LONG-BUFFER=2000
    LONG-BUFFER-DEFAULT=250
    
    DEFAULTS=SERVICE
    CLASS=A, SERVER=A, SERVICE=A, LONG-BUFFER-LIMIT=100
    CLASS=B, SERVER=B, SERVICE=B, LONG-BUFFER-LIMIT=UNLIM
    CLASS=C, SERVER=C, SERVICE=C
  • In the following example, short message buffers are allocated using the keywords NUM-SHORT-BUFFER, SHORT-BUFFER-DEFAULT and SHORT-BUFFER-LIMIT:

    DEFAULTS=BROKER
    NUM-SHORT-BUFFER=2000
    SHORT-BUFFER-DEFAULT=250
    
    DEFAULTS=SERVICE
    CLASS=A, SERVER=A, SERVICE=A, SHORT-BUFFER-LIMIT=100
    CLASS=B, SERVER=B, SERVICE=B, SHORT-BUFFER-LIMIT=UNLIM
    CLASS=C, SERVER=C, SERVICE=C
  • In the following example, servers are allocated using the keywords NUM-SERVER, SERVER-DEFAULT and SERVER-LIMIT:

    DEFAULTS=BROKER
    NUM-SERVER=2000
    SERVER-DEFAULT=250
    
    DEFAULTS=SERVICE
    CLASS=A, SERVER=A, SERVICE=A, SERVER-LIMIT=100
    CLASS=B, SERVER=B, SERVICE=B, SERVER-LIMIT=UNLIM
    CLASS=C, SERVER=C, SERVICE=C

Specifying Attributes for Privileged Services

If privileged services (services with access to unlimited resources) exist, specify UNLIMITED for the attributes CONV-LIMIT, SERVER-LIMIT, LONG-BUFFER-LIMIT and SHORT-BUFFER-LIMIT in the service-specific section of the attribute file.

For example:

DEFAULTS=SERVICE
CONV-LIMIT=UNLIM
LONG-BUFFER-LIMIT=UNLIM
SHORT-BUFFER-LIMIT=UNLIM
SERVER-LIMIT=UNLIM

To ensure a resource reservoir for peak load of privileged services, define more resources than would normally be expected by specifying larger numbers for the Broker attributes that control global resources:

NUM-SERVER
NUM-CONVERSATION
CONV-DEFAULT
LONG-BUFFER-DEFAULT
SHORT-BUFFER-DEFAULT
SERVER-DEFAULT

Maximum Units of Work

The maximum number of units of work (UOWs) that can be active concurrently is specified in the Broker attribute file. The MAX-UOWS attribute can be specified for the Broker globally as well as for individual services. It cannot be calculated automatically. If a service is intended to process UOWs, a MAX-UOWS value must be specified.

If message processing only is to be done, specify MAX-UOWS=0 (zero). The Broker (or the service) will not accept units of work, i.e., it will process only messages that are not part of a UOW. Zero is used as the default value for MAX-UOWS in order to prevent the sending of UOWs to services that are not intended to process them.

Calculating Resources Automatically

To ensure that each service runs without impacting other services, allow the EntireX Broker to calculate resource requirements automatically:

  • Ensure that the attributes that define the default total for the Broker and the limit for each service are not set to UNLIM.

  • Specify AUTO for the Broker attribute that defines the total number of the resource.

  • Specify a suitable value for the Broker attribute that defines the default number of the resource.

The total number required will be calculated from the number defined for each service. The resources that can be calculated this way are Number of Conversations, Number of Servers, Long Message Buffers and Short Message Buffers.

Avoid altering the service-specific definitions at runtime. Doing so could corrupt the conversation consistency. Applications might receive a message such as "NUM-CONVERSATIONS reached" although the addressed service does not serve as many conversations as defined. The same applies to the attributes that define the long and short buffer resources.

Automatic resource calculation has the additional advantage of limiting the amount of memory used to run the EntireX Broker. Over time, you should be able to determine which services need more resources by noting the occurrence of the return code "resource shortage, please retry". You can then increase the resources for these services. To avoid disruption to the user, you could instead allocate a relatively large set of resources initially and then decrease the values using information gained from the Administration Monitor application.

Number of Conversations

To calculate the total number of conversations automatically, ensure that the CONV-DEFAULT Broker attribute and the CONV-LIMIT service-specific attribute are not set to UNLIM anywhere in the attribute file. Specify NUM-CONVERSATION=AUTO and an appropriate value for the CONV-DEFAULT Broker attribute. The total number of conversations will be calculated using the value specified for each service.

For example:

DEFAULTS=BROKER
NUM-CONVERSATION=AUTO
CONV-DEFAULT=200 

DEFAULTS=SERVICE
CLASS=A, SERVER=A, SERVICE=A
CLASS=B, SERVER=B, SERVICE=B, CONV-LIMIT=100
CLASS=C, SERVER=C, SERVICE=C
  • Service A and Service C both need 200 conversations (the default value). Service B needs 100 conversations (CONV-LIMIT=100).

  • Because NUM-CONVERSATIONS is defined as AUTO, the broker calculates a total of 500 conversations (200 + 200 + 100).

  • NUM-CONVERSATIONS=AUTO allows the number of conversations to be flexible without requiring additional specifications. It also ensures that the broker is started with enough resources to meet all the demands of the individual services.

  • AUTO and UNLIM are mutually exclusive. If CONV-DEFAULT or a single CONV-LIMIT is defined as UNLIM, the EntireX Broker cannot determine the number of conversations to use in the calculation, and the EntireX Broker cannot be started.

Number of Servers

To calculate the number of servers automatically, ensure that the SERVER-DEFAULT Broker attribute and the SERVER-LIMIT service-specific attribute are not set to UNLIM anywhere in the attribute file. Specify NUM-SERVER=AUTO and an appropriate value for the SERVER-DEFAULT Broker attribute. The total number of server buffers will be calculated using the value specified for each service.

For example:

DEFAULTS=BROKER
NUM-SERVER=AUTO
SERVER-DEFAULT=250

DEFAULTS=SERVICE
CLASS=A, SERVER=A, SERVICE=A, SERVER-LIMIT=100
CLASS=B, SERVER=B, SERVICE=B
CLASS=C, SERVER=C, SERVICE=C

Long Message Buffers

To calculate the number of long message buffers automatically, ensure that the LONG-BUFFER-DEFAULT Broker attribute and the LONG-BUFFER-LIMIT service-specific attribute are not set to UNLIM anywhere in the attribute file. Specify NUM-LONG-BUFFER=AUTO and an appropriate value for the LONG-BUFFER-DEFAULT Broker attribute. The total number of long message buffers will be calculated using the value specified for each service.

For example:

DEFAULTS=BROKER
NUM-LONG-BUFFER=AUTO
LONG-BUFFER-DEFAULT=250

DEFAULTS=SERVICE
CLASS=A, SERVER=A, SERVICE=A, LONG-BUFFER-LIMIT=100
CLASS=B, SERVER=B, SERVICE=B
CLASS=C, SERVER=C, SERVICE=C

Short Message Buffers

To calculate the number of short message buffers automatically, ensure that the SHORT-BUFFER-DEFAULT Broker attribute and the SHORT-BUFFER-LIMIT service-specific attribute are not set to UNLIM anywhere in the attribute file. Specify NUM-SHORT-BUFFER=AUTO and an appropriate value for the SHORT-BUFFER-DEFAULT Broker attribute. The total number of short message buffers will be calculated using the value specified for each service.

For example:

DEFAULTS=BROKER
NUM-SHORT-BUFFER=AUTO
SHORT-BUFFER-DEFAULT=250

DEFAULTS=SERVICE
CLASS=A, SERVER=A, SERVICE=A
CLASS=B, SERVER=B, SERVICE=B, SHORT-BUFFER-LIMIT=100
CLASS=C, SERVER=C, SERVICE=C

Dynamic Memory Management

Dynamic memory management is a feature to handle changing Broker workload without any restart of the Broker task. It increases the availability of the Broker by using various memory pools for various Broker resources and by being able to use a variable number of pools for the resources.

If more memory is needed than currently available, another memory pool is allocated for the specific type of resource. If a particular memory pool is no longer used, it will be deallocated.

The following Broker attributes can be omitted if DYNAMIC-MEMORY-MANAGEMENT=YES has been defined:

  • NUM-CLIENT

  • NUM-CMDLOG-FILTER

  • NUM-COMBUF

  • NUM-CONV[ERSATION]

  • NUM-LONG[-BUFFER]

  • NUM-PUBLICATION

  • NUM-PUBLISHER

  • NUM-SERVER

  • NUM-SERVICE

  • NUM-SERVICE-EXTENSION

  • NUM-SHORT[-BUFFER]

  • NUM-SUBSCRIBER

  • NUM-SUBSCRIBER-TOTAL

  • NUM-TOPIC

  • NUM-TOPIC-EXTENSION

  • NUM-TOPIC-TOTAL

  • NUM-UOW|MAX-UOWS|MUOW

  • NUM-WQE

If you want statistics on allocation and deallocation operations in Broker, you can configure Broker to create a storage report with the attribute STORAGE-REPORT. See Storage Report below.

Note:
To ensure a stable environment, some pools of Broker are not deallocated automatically. The first pools of type COMMUNICATION, CONVERSATION, CONNECTION, HEAP, PARTICIPANT, PARTICIPANT EXTENSION, SERVICE ATTRIBUTES, SERVICE, SERVICE EXTENSION, TIMEOUT QUEUE, TRANSLATION, WORK QUEUE are excluded from the automatic deallocation even when they have not been used for quite some time. Large pools cannot be reallocated under some circumstances if the level of fragmentation in the address space has been increased in the meantime.

Dynamic Worker Management

Dynamic worker management is a feature to handle the fluctuating broker workload without restarting the Broker task. It adjusts the number of running worker tasks according to current workload. The initial portion of worker tasks started at Broker startup is still determined by NUM-WORKER.

If more workers are needed than currently available, another worker task is started. If a worker task is no longer needed, it will be stopped.

The following Broker attributes are used for the configuration if DYNAMIC-WORKER-MANAGEMENT=YES has been defined:

  • WORKER-MAX

  • WORKER-MIN

  • WORKER-NONACT

  • WORKER-QUEUE-DEPTH

  • WORKER-START-DELAY

The following two attributes are very performance-sensitive:

  • Attribute WORKER-QUEUE-DEPTH defines the number of unassigned user requests in the input queue before a new worker task is started.

  • Attribute WORKER-START-DELAY defines the time between the last worker task startup and the next check for another possible worker task startup. It is needed to consider the time for activating a worker task.

Both attributes depend on the environment, in particular the underlying operating system and the hardware. The goal is to achieve high-performance user request processing without starting too many worker tasks.

A good starting point to achieve high performance is not to change the attributes and to observe the performance of the application programs after activating the dynamic worker management.

If broker attribute DYNAMIC-WORKER-MANAGEMENT=YES is set, operator commands are available under z/OS to deactivate and subsequently reactivate dynamic worker management.

The following section illustrates the two different modes of dynamic worker management:

  • Scenario 1
    DYNAMIC-WORKER-MANAGEMENT=YES 
    NUM-WORKER = 5 
    WORKER-MIN = 1 
    WORKER-MAX = 32

    Broker is started with 5 worker tasks and then dynamically varies the number of worker tasks within the range from WORKER-MIN=1 to WORKER-MAX=32 due to DYNAMIC-WORKER-MANAGEMENT=YES.

  • Scenario 2
    DYNAMIC-WORKER-MANAGEMENT=NO 
    NUM-WORKER = 5 
    WORKER-MIN = 1 
    WORKER-MAX = 32

    Broker is started with 5 worker tasks. The WORKER-MIN/MAX attributes are ignored due to DYNAMIC-WORKER-MANAGEMENT=NO.

Storage Report

You can create an optional report file that provides details about all activities to allocate or to deallocate memory pools. This section details how to create the report and provides a sample report.

See also Broker-specific attribute STORAGE-REPORT.

Creating a Storage Report

Use Broker's global attribute STORAGE-REPORT with the value YES. If attribute value YES is supplied, all memory pool operations will be reported if the output mechanism is available. If the value NO is specified, no report will be created.

Platform-specific Rules

DDNAME ETBSREP assigns the report file. Format RECFM=FB, LRECL=121 is used.

Sample Storage Report

The following is an excerpt from a sample STORAGE report.

EntireX 8.1.0.00     STORAGE Report     2009-06-26 12:28:58    Page     1                                                
                                                                                                                         
Identifier                  Address            Size             Total         Date       Time      Action                
KERNEL POOL                 0x25E48010     407184 bytes     407184 bytes  2009-06-26 12:28:58.768  Allocated             
HEAP POOL                   0x25EB4010    1050692 bytes    1457876 bytes  2009-06-26 12:28:58.769  Allocated             
COMMUNICATION POOL          0x25FB5010   16781380 bytes   18239256 bytes  2009-06-26 12:28:58.769  Allocated             
ACCOUNTING POOL             0x26FB7010     762052 bytes   19001308 bytes  2009-06-26 12:28:58.769  Allocated             
BROKER POOL                 0x27072010      61540 bytes   19062848 bytes  2009-06-26 12:28:58.775  Allocated             
CONVERSATION POOL           0x27082010     368964 bytes   19431812 bytes  2009-06-26 12:28:58.775  Allocated             
CONNECTION POOL             0x270DD010     233668 bytes   19665480 bytes  2009-06-26 12:28:58.779  Allocated             
LONG MESSAGES POOL          0x27117010    4395204 bytes   24060684 bytes  2009-06-26 12:28:58.782  Allocated             
SHORT MESSAGES POOL         0x27549010    3703876 bytes   27764560 bytes  2009-06-26 12:28:58.806  Allocated             
PARTICIPANT POOL            0x278D2010     134244 bytes   27898804 bytes  2009-06-26 12:28:58.827  Allocated             
PARTICIPANT EXTENSION POOL  0x278F3010      36996 bytes   27935800 bytes  2009-06-26 12:28:58.829  Allocated             
PROXY QUEUE POOL            0x278FD010      26724 bytes   27962524 bytes  2009-06-26 12:28:58.829  Allocated             
SERVICE ATTRIBUTES POOL     0x27904010     131668 bytes   28094192 bytes  2009-06-26 12:28:58.829  Allocated             
SERVICE POOL                0x27925010      54372 bytes   28148564 bytes  2009-06-26 12:28:58.830  Allocated             
SERVICE EXTENSION POOL      0x27933010      32900 bytes   28181464 bytes  2009-06-26 12:28:58.831  Allocated             
TIMEOUT QUEUE POOL          0x2793C010      87268 bytes   28268732 bytes  2009-06-26 12:28:58.831  Allocated             
TRANSLATION POOL            0x27952010     179300 bytes   28448032 bytes  2009-06-26 12:28:58.832  Allocated             
UNIT OF WORK POOL           0x2797E010     176324 bytes   28624356 bytes  2009-06-26 12:28:58.834  Allocated             
WORK QUEUE POOL             0x279AA010     391268 bytes   29015624 bytes  2009-06-26 12:28:58.835  Allocated             
BLACKLIST POOL              0x27A0A010      42084 bytes   29057708 bytes  2009-06-26 12:28:58.838  Allocated             
SUBSCRIPTION POOL           0x27A15010     344148 bytes   29401856 bytes  2009-06-26 12:28:58.839  Allocated             
TOPIC ATTRIBUTES POOL       0x27A6A010     129620 bytes   29531476 bytes  2009-06-26 12:28:58.841  Allocated             
TOPIC POOL                  0x26FB6068       2952 bytes   29534428 bytes  2009-06-26 12:28:58.842  Allocated             
TOPIC EXTENSION POOL        0x27A8A010      30852 bytes   29565280 bytes  2009-06-26 12:28:58.842  Allocated             
PSTORE SUBSCRIBER POOL      0x27A92010      33892 bytes   29599172 bytes  2009-06-26 12:28:58.843  Allocated             
PSTORE TOPIC POOL           0x27A9B010      19540 bytes   29618712 bytes  2009-06-26 12:28:58.843  Allocated             
COMMUNICATION POOL          0x25FB5010   16781380 bytes   12837332 bytes  2009-06-26 12:30:58.514  Deallocated           
ACCOUNTING POOL             0x26FB7010     762052 bytes   12075280 bytes  2009-06-26 12:30:58.515  Deallocated           
BROKER POOL                 0x27072010      61540 bytes   12013740 bytes  2009-06-26 12:30:58.516  Deallocated           
CONVERSATION POOL           0x27082010     368964 bytes   11644776 bytes  2009-06-26 12:30:58.518  Deallocated           
CONNECTION POOL             0x270DD010     233668 bytes   11411108 bytes  2009-06-26 12:30:58.519  Deallocated           
LONG MESSAGES POOL          0x27117010    4395204 bytes    7015904 bytes  2009-06-26 12:30:58.520  Deallocated           
SHORT MESSAGES POOL         0x27549010    3703876 bytes    3312028 bytes  2009-06-26 12:30:58.526  Deallocated           
PROXY QUEUE POOL            0x278FD010      26724 bytes    3285304 bytes  2009-06-26 12:30:58.530  Deallocated           
SUBSCRIPTION POOL           0x27A15010     344148 bytes    2941156 bytes  2009-06-26 12:30:58.530  Deallocated           
TOPIC ATTRIBUTES POOL       0x27A6A010     129620 bytes    2811536 bytes  2009-06-26 12:30:58.531  Deallocated           
TOPIC POOL                  0x26FB6068       2952 bytes    2808584 bytes  2009-06-26 12:30:58.531  Deallocated           
TOPIC EXTENSION POOL        0x27A8A010      30852 bytes    2777732 bytes  2009-06-26 12:30:58.531  Deallocated           
TIMEOUT QUEUE POOL          0x2793C010      87268 bytes    2690464 bytes  2009-06-26 12:30:58.532  Deallocated           
UNIT OF WORK POOL           0x2797E010     176324 bytes    2514140 bytes  2009-06-26 12:30:58.533  Deallocated           
WORK QUEUE POOL             0x279AA010     391268 bytes    2122872 bytes  2009-06-26 12:30:58.533  Deallocated           
BLACKLIST POOL              0x27A0A010      42084 bytes    2080788 bytes  2009-06-26 12:30:58.534  Deallocated           
PSTORE SUBSCRIBER POOL      0x27A92010      33892 bytes    2046896 bytes  2009-06-26 12:30:58.534  Deallocated           
PSTORE TOPIC POOL           0x27A9B010      19540 bytes    2027356 bytes  2009-06-26 12:30:58.534  Deallocated           
PARTICIPANT POOL            0x278D2010     134244 bytes    1893112 bytes  2009-06-26 12:49:25.817  Deallocated           
PARTICIPANT EXTENSION POOL  0x278F3010      36996 bytes    1856116 bytes  2009-06-26 12:49:25.818  Deallocated           
SERVICE ATTRIBUTES POOL     0x27904010     131668 bytes    1724448 bytes  2009-06-26 12:49:25.818  Deallocated           
SERVICE POOL                0x27925010      54372 bytes    1670076 bytes  2009-06-26 12:49:25.818  Deallocated           
SERVICE EXTENSION POOL      0x27933010      32900 bytes    1637176 bytes  2009-06-26 12:49:25.819  Deallocated           
TRANSLATION POOL            0x27952010     179300 bytes    1457876 bytes  2009-06-26 12:49:25.819  Deallocated           
HEAP POOL                   0x25EB4010    1050692 bytes     407184 bytes  2009-06-26 12:49:25.820  Deallocated           
KERNEL POOL                 0x25E48010     407184 bytes          0 bytes  2009-06-26 12:49:25.820  Deallocated
Header Description
Identifier Name of the memory pool.
Address Start address of the memory pool.
Size Size of the memory pool.
Total Total size of all obtained memory pools.
Date, Time Date and time of the action.
Action The action of Broker. The following actions are currently supported:
Allocated: memory pool is allocated .
Deallocated: memory pool is deallocated.

Maximum TCP/IP Connections per Communicator

This table shows the maximum number of TCP/IP connections per communicator:

Platform Maximum Number of TCP/IP Connections per Communicator
AIX 2,048
BS2000/OSD 2,048
HP-UX 2,048
Linux 4,096
Solaris 65,356
Windows 4,096
z/OS 16,384
z/VSE 2,048

With the Broker-specific attribute POLL, these restrictions can be lifted under z/OS, UNIX and z/VSE. See POLL.

See also MAX-CONNECTIONS under TCP-OBJECT (Struct INFO_TCP) under Information Reply Structures in the Broker CIS documentation.

Note for z/OS

Under z/OS, the following message may appear in the broker log:

ETBD0286 Diagnostic Values:
	accept: 124, EDC5124I Too many open files.errno2: 84607302 050B0146

The most common reason for this TCP/IP Communicator diagnostic message is the limitation of open files per user. The value of MAXFILEPROC in the BPXPRM00 parmlib member should be greater than the expected number of TCP/IP connections.