fix(cmem.l5): use instances cache instead of poolsize

[RobinzZH]

Checklist:

• test cases has added or updated
• documentation has added or updated
• commit message follows the convention commit guidelines

[codecov-io]

Codecov Report

Merging #173 into dev will decrease coverage by 0.1%.
The diff coverage is 9.09%.

@@            Coverage Diff             @@
##              dev     #173      +/-   ##
==========================================
- Coverage   39.19%   39.08%   -0.11%     
==========================================
  Files          43       43              
  Lines        2424     2433       +9     
==========================================
+ Hits          950      951       +1     
- Misses       1474     1482       +8

Impacted Files	Coverage Δ
bin/tsw/pool/cmem.l5.js	18.82% <9.09%> (-0.92%)	⬇️

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