SYSEAM files temporarily store the EAM files of the users.
Temporary means that the files are only stored short-term in the SYSEAM system file. After the job terminates successfully the temporary EAM files created during the job are deleted again.
A SYSEAM file can be set up on all pubsets. The name is
:<pvsid>:$TSOS.SYSEAM:
<pvsid> designates the pubset. In this case there is exactly one SYSEAM file.
If a SYSEAM file with the corresponding name was created by systems support on the default pubset of a user, then the user accesses the SYSEAM file which is on his default pubset. However, if there is no SYSEAM file on the default pubset of a user, then the user accessed the SYSEAM file on his home pubsets.
Defining values for SYSEAM
Systems support can specify the following attributes for a SYSEAM file for a specific pubset. They apply equally to all SYSEAM files created on a pubset:
Minimum size
Value for secondary allocation
Size of a cache for a SYSEAM file in class 4 memory (however, this is only used for the SYSEAM file on the home pubset).
These attributes are entered in the corresponding master catalog entry with the help of the ADD-MASTER-CATALOG-ENTRY and/or MODIFY-MASTER-CATALOG-ENTRY commands.
A SYSEAM file is created (at the latest during the first access using the EAM access method) whose size is at least as large as the minimum size defined for it. If there is not enough space anymore for a SYSEAM file, the SYSEAM file is extended dynamically by its secondary allocation value until its maximum size is reached.
Once the EAM load starts to drop again, the extra space now left in the SYSEAM file is freed dynamically piece by piece (in blocks the size of the secondary allocation value) until it reaches its lower limit.
Default setting by means of system parameters
If there are no entries stored in the master catalog entry of a pubset for the attributes of a SYSEAM file, then the system parameters EAMMIN, EAMSEC and EAMMEM are used for the minimum size, the value for secondary allocation and the size of the cache for the SYSEAM file of the home pubset. Furthermore, the space available for a single user alone in a SYSEAM file can be specified with the system parameter EAMSIZ.
They are defined in the startup parameter file in the section with the SYSOPT-CLASS2 identifier. The values of the system parameters named can be displayed with the help of the SHOW-SYSTEM-PARAMETERS command.
SYSEAM files on shared pubsets
The handling of SYSEAM files on a shared pubset is controlled by the system parameter EAMSPVS:
either there is exactly one SYSEAM file on the affected shared pubset (SPVS) for the pubset master of the shared pubset (EAMSPVS=0). The pubset slaves participating in the shared pubset network cannot use this SYSEAM file.
or every system participating in the shared pubset network (i.e. on the pubset master as well as on every pubset slave) can work with a SYSEAM file on this shared pubset (EAMSPVS=1).
The name of the SYSEAM file concerned is
:<pvsid>:$TSOS.SYSEAM.<sysid>:.<sysid>is a three-digit number and designates the identification of the importing system in the shared pubset network (“system identification”). It can be determined using the SHOW-PUBSET-ATTRIBUTES command.There is consequently a SYSEAM file with the suffix
<sysid>in this case for every importing system on the pubset indicated by<pvsid>.If in this case systems support creates a file with the name
:<pvsid>:$TSOS.SYSEAM, it is not used.The values for EAMMIN, EAMSEC and EAMSIZ equally apply then to all SYSEAM files created on a pubset (see above).