CHGMODD (Change Mode Description)
CHGMODD Command syntax diagram
Purpose
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).
Required Parameters
- MODD
- Specifies the name of the mode description being changed.
Optional Parameters
- COS
- Specifies the class-of-service associated with the mode.
*SAME: The value does not change.
class-of-service-name: Specify the class-of-service name in the mode description. Valid class-of-service names are shown below:
- #CONNECT
- #BATCH
- #INTER
- #BATCHSC
- #INTERSC
- MAXSSN
- Specifies the maximum number of active sessions that are established for this mode. This number must be greater than or equal to the number of locally controlled sessions on the local system (as specified in the LCLCTLSSN parameter) plus the number of locally controlled sessions specified at the remote location.
*SAME: The value does not change.
maximum-number-of-sessions: Specify a value ranging from 1 through 512 for the maximum number of active sessions.
- MAXCNV
- Specifies the maximum number of active conversations allowed by this mode. The maximum number of active conversations is the sum of synchronous and asynchronous conversations; this value must be greater than or equal to the value specified by the MAXSSN parameter. A synchronous conversation is a conversation in which both the source and target programs are communicating. An asynchronous conversation is a conversation in which the source program has detached from the conversation, but there is still data to be read by the target program.
*SAME: The value does not change.
maximum-number-of-conversations: Specify a value ranging from 1 through 512 for the maximum number of conversations.
- LCLCTLSSN
- Specifies the minimum number of active locally controlled sessions that can be established for this mode. This value must be less than or equal to the value specified in the MAXSSN parameter.
*SAME: The value does not change.
locally-controlled-sessions: Specify a value ranging from 0 through 512 for the minimum number of locally controlled sessions.
- PREESTSSN
- Specifies the maximum number of locally controlled pre-established sessions (established when the mode is started). Additional sessions are established when required up to the value specified in the MAXSSN parameter; this value must be less than or equal to the value specified in the LCLCTLSSN parameter.
*SAME: The value does not change.
number-of-pre-established-sessions: Specify a value ranging from 0 through 512 for the maximum number of locally controlled sessions established when the mode is started.
- 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 the loss of data.
Note: To ensure an optimum rate, the value *CALC is recommended. *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.
- INPACING
- Specifies the SNA pacing value used to schedule the incoming request units (RUs).
*SAME: The value does not change.
inbound-pacing-value: Specify a value ranging from 0 through 63 for the limiting value.
- OUTPACING
- Specifies the SNA pacing value used for outgoing request units (RUs).
*SAME: The value does not change.
outbound-pacing-value: Specify a value ranging from 0 through 63 as the limiting value.
- MAXLENRU
- Specifies the maximum request unit (RU) length (in bytes) allowed.
Note: To ensure an optimum length, the value *CALC is recommended. *SAME: The value does not change.
*CALC: The system determines the value to use.
maximum-request-unit-length: Specify a value ranging from 241 through 32768 as the maximum length for 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
- 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 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 for the 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 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 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).
- INDTACPR
- Specifies the desired level of compression for inbound data. No data compression occurs if DTACPR(*NONE) is specified.
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. The LZ12 requires the most storage and processing time of the LZ algorithms; however, it compresses the data stream the most.
*NONE: No compression occurs.
- OUTDTACPR
- Specifies the desired level of compression for outbound data. No data compression occurs if DTACPR(*NONE) is specified.
*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. The LZ12 requires the most storage and processing time of the LZ algorithms; however, it compresses the data stream the most.
*NONE: No compression occurs.
- 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 OS/400 is installed along with the Cryptographic Processor feature or the Cryptographic Processor-Commercial feature.
- TEXT
- Specifies the text that briefly describes the mode description. More information is in Commonly used parameters.
*SAME: The value does not change.
*BLANK: Text is not specified.
'description': Specify no more than 50 characters of text, enclosed in apostrophes.
Example for CHGMODD
CHGMODD MODD(MODE1) PREESTSSN(3)This command changes the number of pre-established sessions for MODE1 to three.
Error messages for CHGMODD
*ESCAPE Messages
- CPF262D
- Mode description &1 not changed.