Change Mode Description (CHGMODD)

The Change Mode Description (CHGMODD) command changes a mode description for advanced-program-to-program communications (APPC) devices. APPC support uses Systems Network Architecture (SNA).

Parameters

Keyword Description Choices Notes
MODD Mode description Name Required, Key, Positional 1
COS Class-of-service Communications name, *SAME, #CONNECT, #BATCH, #INTER, #BATCHSC, #INTERSC Optional
MAXSSN Maximum sessions 1-512, *SAME Optional
MAXCNV Maximum conversations 1-512, *SAME Optional
LCLCTLSSN Locally controlled sessions 0-512, *SAME Optional
PREESTSSN Pre-established sessions 0-512, *SAME Optional
MAXINPAC Maximum inbound pacing value 1-32767, *SAME, *CALC Optional
INPACING Inbound pacing value 0-63, *SAME Optional
OUTPACING Outbound pacing value 0-63, *SAME Optional
MAXLENRU Maximum length of request unit 241-32767, *SAME, *CALC Optional
DTACPR Data compression 1-2147483647, *SAME, *NETATR, *NONE, *ALLOW, *REQUEST, *REQUIRE Optional
INDTACPR Inbound data compression *SAME, *RLE, *LZ9, *LZ10, *LZ12, *NONE Optional
OUTDTACPR Outbound data compression *SAME, *RLE, *LZ9, *LZ10, *LZ12, *NONE Optional
SLE Session level encryption *ALL, *NONE, *SAME Optional
TEXT Text 'description' Character value, *SAME, *BLANK Optional

Mode description (MODD)

Specifies the name of the mode description.

This is a required parameter.

This is a required parameter.

Class-of-service (COS)

Specifies the path control network characteristics (represented by a class-of-service description) used by advanced peer-to-peer networking (APPN).

class-of-service-name
Specify the class-of-service name.

Note: The class-of-service name will be ignored if using mode for APPC.

*SAME
The value does not change.

Maximum sessions (MAXSSN)

Specifies the maximum number of active sessions that are established for this mode. This number must be greater than or equal to the sum of the number of locally controlled sessions as specified on the Locally controlled sessions prompt (LCLCTLSSN) and the number of locally controlled sessions specified at the remote location.

maximum-number-of-sessions
Specify the maximum number of sessions.

Valid values range from 1 to 512.

*SAME
The value does not change.

Maximum conversations (MAXCNV)

Specifies the maximum number of conversations that can be established at the same time with the remote system. The maximum number of conversations is the sum of synchronous and asynchronous conversations; this value must be greater than or equal to the value specified by the Maximum sessions prompt (MAXSSN parameter). A synchronous conversation is a conversation where both the source and the target programs are communicating. An asynchronous conversation is a conversation where the source program has detached itself from the conversation, but data is still being read by the target program.

maximum-number-of-conversations
Specify the maximum number of conversations. Valid values range from 1 to 512.
*SAME
The value does not change.

Locally controlled sessions (LCLCTLSSN)

Specifies the minimum number of locally controlled sessions that must be active to establish this mode. This value must be less than or equal to the value specified in the Maximum sessions prompt (MAXSSN parameter).

locally-controlled sessions
Specify the number of locally-controlled sessions used as source sessions. Valid values range from 0 to 512.
*SAME
The value does not change.

Pre-established sessions (PREESTSSN)

Specifies the maximum number of locally-controlled sessions that are established when the mode is started. Additional sessions are established as required, up to the maximum number of locally-controlled sessions specified in the Maximum sessions prompt (MAXSSN parameter). This value must be less than or equal to the value specified in the Locally controlled sessions prompt (LCLCTLSSN parameter).

number-of-established-sessions
Specify the maximum number of concurrent locally-controlled sessions established when the mode is started. Valid values range from 0 to 512.
*SAME
The value does not change.

Maximum inbound pacing value (MAXINPAC)

Specifies the maximum SNA pacing value used to schedule incoming request units (RUs). Pacing is established by the receiving system to control the rate of transmission of the sending system to prevent loss of data.

Note: To ensure an optimum rate, the value *CALC is recommended.

*SAME
The value does not change.
*CALC
The system determines the value to use. The value is calculated to be 2*INPACING, which is two times the value specified on the INPACING parameter.
maximum-inbound-pacing
Specify a value, ranging from 1 through 32767 in RUs, for the maximum inbound pacing value.

Inbound pacing value (INPACING)

Specifies the Systems Network Architecture (SNA) pacing value used to schedule the incoming request units (RUs).

7
A value of 7 is used as the RU pacing value.
inbound-pacing-value
Specify a value from 0 to 63 used as the limiting value.
*SAME
The value does not change.

Outbound pacing value (OUTPACING)

Specifies the SNA pacing value used for outgoing request units (RUs).

7
A value of 7 is used as the RU pacing value.
outbound-pacing-value
Specify a value from 0 to 63 used as the limiting value.
*SAME
The value does not change.

Maximum length of request unit (MAXLENRU)

Specifies the maximum request unit (RU) length allowed.

Note: To ensure an optimum length, the value *CALC is recommended.

*CALC
The system calculates the value to use.
maximum-request-unit-length
Specify a value, ranging from 241 through 32767 in bytes, for the maximum length of incoming request units.

Some other common values are:

  • SDLC lines: 256, 512, 1024, 2048
  • Token-Ring Network lines: 256, 512, 1024, 1985
  • X.25 (QLLC) lines: 247, 503, 1015
  • X.25 (ELLC) lines: 241, 497, 1009

More information is in the Communications Configuration book, SC41-5401 book.

*SAME
The value does not change.

Data compression (DTACPR)

Specifies whether data compression is used.

*SAME
The value does not change.
*NETATR
The value from the DTACPR network attributes is used.
*NONE
Compression is not allowed on the session.
*ALLOW
Data compression is allowed on the session by the local system if requested by a remote system. The local system does not request compression.

If data compression is requested by the remote system, the data compression levels used by the session are the lower of the requested levels and the levels specified on the Inbound data compression and Outbound data compression prompts (INDTACPR and OUTDTACPR parameters).

*REQUEST
Data compression is requested on the session by the local system. However, the request can be refused or changed to lower compression levels by the remote system. Data compression is allowed on the session if requested by the remote system. The requested compression levels for inbound and outbound data are the levels specified on the Inbound data compression and Outbound data compression prompts (INDTACPR and OUTDTACPR parameters).

If data compression is requested by the remote system, the data compression levels used by the session are the lower of the requested levels and the levels specified on the Inbound data compression and Outbound data compression prompts (INDTACPR and OUTDTACPR parameters).

*REQUIRE
Data compression is required on the session. If the remote system does not accept the local system's exact required levels of compression, the session is not established.

The data compression levels that the local system require are the levels specified on the Inbound data compression and Outbound data compression prompts (INDTACPR and OUTDTACPR parameters).

line-speed
Specify the maximum line speed at which data is compressed. If the line speed of the link used by the session is less than or equal to this specified line speed, data compression is used for the session as if *REQUEST is specified. Otherwise, compression is used for the session as if *ALLOW is specified. Valid values range from 1 through 2147483647 in bits per second (bps).

Inbound data compression (INDTACPR)

Specifies the desired level of compression for inbound data. No data compression occurs if *NONE is specified on the Data compression prompt (DTACPR parameter).

Note: Adaptive dictionary-based compression is a dynamic compression algorithm, similar to Lempel-Ziv, that compresses previously seen strings to 9-, 10-, and 12-bit codes. This algorithm is referred to as LZ in the following parameters.

*SAME
The value does not change.
*RLE
The Run Length Encoding (RLE) algorithm is used. RLE substitutes a 1- or 2-byte sequence in the data stream for each repeated occurrence of the same character. This algorithm requires no storage and less processing time than the other options.
*LZ9
The LZ algorithm with the 9-bit code for repeated substrings in the data stream is used. These codes refer to entries in a common dictionary, created as the data flows between the sender and receiver. The LZ algorithms require storage and extra processing time. The LZ9 requires the least storage and processing time of the LZ algorithms; however, it compresses the data stream the least.
*LZ10
The LZ algorithm with the 10-bit code for repeated substrings in the data stream is used. These codes refer to entries in a common dictionary, created as the data flows between the sender and receiver. The LZ algorithms require storage and extra processing time. The LZ10 table algorithm requires more storage and processing time than the LZ9, but less than the LZ12. The LZ10 compresses the data stream more than the LZ9, but less than the LZ12.
*LZ12
The LZ algorithm with the 12-bit code for repeated substrings in the data stream is used. These codes refer to entries in a common dictionary, created as the data flows between the sender and receiver. The LZ algorithms require storage and extra processing time. LZ12 requires the most storage and processing time of the LZ algorithms; however, it compresses the data stream the most.
*NONE
No compression occurs.

Outbound data compression (OUTDTACPR)

Specifies the desired level of compression for outbound data. No data compression occurs if *NONE is specified on the Data compression prompt (DTACPR parameter).

*SAME
The value does not change.
*RLE
The Run Length Encoding (RLE) algorithm is used. RLE substitutes a 1- or 2-byte sequence in the data stream for each repeated occurrence of the same character. This algorithm requires no storage and less processing time than the other options.
*LZ9
The LZ algorithm with the 9-bit code for repeated substrings in the data stream is used. These codes refer to entries in a common dictionary, created as the data flows between the sender and receiver. The LZ algorithms require storage and extra processing time. The LZ9 requires the least storage and processing time of the LZ algorithms; however, it compresses the data stream the least.
*LZ10
The LZ algorithm with the 10-bit code for repeated substrings in the data stream is used. These codes refer to entries in a common dictionary, created as the data flows between the sender and receiver. The LZ algorithms require storage and extra processing time. The LZ10 table algorithm requires more storage and processing time than the LZ9, but less than the LZ12. The LZ10 compresses the data stream more than the LZ9, but less than the LZ12.
*LZ12
The LZ algorithm with the 12-bit code for repeated substrings in the data stream is used. These codes refer to entries in a common dictionary, created as the data flows between the sender and receiver. The LZ algorithms require storage and extra processing time. LZ12 requires the most storage and processing time of the LZ algorithms; however, it compresses the data stream the most.
*NONE
No compression occurs.

Session level encryption (SLE)

Specifies the desired level of session encryption.

*SAME
The value does not change.
*NONE
No data is encrypted or decrypted.
*ALL
All data is encrypted before it is sent out to the network and is decrypted as it is received from the network.

Note: The use of session level encryption requires that IBM Common Cryptographic Architecture Services for i5/OS is installed along with the Cryptographic Processor feature or the Cryptographic Processor-Commercial feature.

Text 'description' (TEXT)

Specifies the text that briefly describes the object.

*BLANK
No text is specified.
character-value
Specify no more than 50 characters of text, enclosed in apostrophes.
*SAME
The value does not change.

Examples 

CHGMODD   MODD(MODE1)  PREESTSSN(3)

This command changes the number of pre-established sessions for MODE1 to three.

Error messages

*ESCAPE Messages

CPF262D
Mode description &1 not changed.