4. EXCEPTIONS › 4.3 Detailed Exception Descriptions › 02906: Largest Free Block of SQA Less Than Minimum

02906: Largest Free Block of SQA Less Than Minimum

FILE: Virtual Storage System Usage File
SAS FILE NAME: DAYS.SCPVSM01
SOURCE LOCATION: prefix.MICS.USER.SOURCE(DYRMFEXC)

SEVERITY: Impacting            (SEVERITY='I')
MANAGEMENT AREA: Performance   (MGMTAREA='PERFORMANCE')

PURPOSE:  Detect fragmented or overcommitted System Queue
Area (SQA).

RATIONALE:  When storage allocations in the SQA are made and
released over a long period of time, it is possible for the
free space to be so fragmented that there is no single
contiguous area large enough to satisfy an allocation request
even though the sum of the fragments is more than the
request.  In this case, an unconditional allocation request
will fail.

DEFINITION:  This exception is detected when the largest free
block of SQA is less than an installation-defined minimum
size.

EXCEPTION STATEMENTS:  The SAS statements identifying the
exception situation and describing the condition are stored
in the source member named in SOURCE LOCATION and are
described below:

/* *****************************************************
**  02906 LARGEST FREE BLOCK OF SQA LESS THAN MINIMUM **
***************************************************** */
IF VSMABSQL NE .  THEN IF VSMABSQL LT kbytes
 THEN DO;
  EXCCODE='02906'; SEVERITY='I'; MGMTAREA='PERFORMANCE';
  EXCDESC1='LARGEST FREE BLOCK OF SQA LESS THAN MINIMUM';
  EXCDESC2='SIZE=' !! PUT(VSMABSQL,4.) !! ' KBYTES';
  LINK HIT;
END;

THRESHOLD MODIFICATION:  The user should modify the kbyte
value according to the following convention:

kbyte - The minimum size of the largest free block of SQA.  A
test for a value less than 16 KB would appear as:

VSMABSQL LT 16