PCB segment type format

The IMS catalog PCB segment type contains metadata about a program control block definition.

Information in this segment type is generated based on the parameters of the PCB statement of the PSBGEN utility.
Segment name
PCB
Parent name
PSB
Sequence field
PCBSEQ
Segment length
288 bytes
Table 1. PCB segment type format
Offset (bytes) Length (bytes) Data type Field name Description Unique key field
1 2 X LEN Length of this segment  
3 2 X CTL Control field  
5   2 X PCBSEQ Sequence field, type = U X
  5 2 X SEQNUM Sequence number  
9 8 C IMSNAME The name of the physical or logical DBD that is the primary source of database segments for this PCB. Other databases may be added to the logical data structure for this PCB with secondary indexes and cross references.

In an alternate PCB, this field is the name of the LTERM that the output message is sent to.

  
17 8 C PCBNAME 8-character IMS name of this PCB based on the PCBNAME or LABEL parameter of the PCB statement.  
25 8 C LABEL 8-character IMS name of this PCB based on the PCB label parameter. If this field contains data, the PCBNAME field contains blanks.  
33 4 C TYPE Identifies whether this PCB is a standard or alternate PCB. A standard PCB returns its output message to the source of the input message. An alternate PCB returns the message to a different destination such as a terminal or transaction queue.
DB
Standard PCB
TP
Alternate PCB
  
37 4 C PROCOPT Identifies the processing options for this PCB. Processing options define what types of operations an application program using the PCB can perform. There can be up to four options for one PCB.  
41 8 C PROCSEQ The name of a secondary index for the database identified in the IMSNAME field. Application programs that use this PCB use the processing sequence of the secondary index rather than the primary database.  
49 8 C PROCSEQD The name of a secondary index for the Fast Path database identified in the IMSNAME field. Application programs that use this PCB use the processing sequence of the secondary index rather than the primary Fast Path database.  
57 2 X KEYLEN The number of bytes in the longest concatenated key for a hierarchical path of sensitive segments used in the data structure accessed with this PCB.  
59 2 X COPIES The number of runtime copies that exist for this PCB. This value is used for XQUERY processing.  
61 4 C VIEW Identifies that this PCB for a Fast Path database uses either the DEDB commit view or the MSDB commit view.  
65 1 C ALTRESP Identifies if this alternate PCB can be used instead of the standard I/O PCB for terminal response messages in response mode, conversational mode, or exclusive mode.  
66 1 C EXPRESS Identifies whether queued messages are sent (Y) or backed out (N) by this alternate PCB if the application program using it abends.  
67 1 C MODIFY Specifies if the destination name for this alternate PCB can be dynamically modified.  
68 1 C SAMETRM Identifies if IMS verifies that the destination logical terminal for this alternate PCB is the same as the logical terminal that sent the input message.  
69 1 C SB Identifies if this PCB is buffered with sequential buffering when possible.  
70 1 C POS Identifies whether this PCB uses single (S) or multiple (M) positioning in the target data structure.  
71 1 C LIST Identifies if this PCB is included in the PCB list passed to an application program when it is given control.  
72 1 C PSELOPT Indicates how this PCB logically groups user partition databases for qualified GN calls without SSA processing before the end of the data is reached in the user partition databases:
M
The selected user partition database and subsequent user partition databases within a user data partition are grouped as they are physically defined in the NAME field of the LCHILD definition of the primary Fast Path database DBD.
S
Only the selected user partition database is used by the PCB. Subsequent user partition databases are not added to the logical group.

This field is only used for Fast Path secondary index databases.

  
73 1 C FILLER01 Reserved  
74 7 C ACCESS Indicates whether this PCB accesses the target database using the normal secondary index or a separate logical database.  
81 128 C NAME External alias name of this PCB  
209 13 C DBDTS DBDGEN timestamp  
222 4 X DBVER Requested DBD version  
226 63 N/A N/A Reserved bytes